Sedimentation device having an inflow distributor element.

© Patent holder (s):

PWN Technologies BV in Velserbroek.

(72) Inventor (s):

Petrus Cornells Camp in Egmond ad Hoef.

© Authorized representative:

Dr. R. Jorritsma et al. In The Hague.

© Sedimentation device having an inflow distributor element.

© The invention relates to a counter current gravity driven sedimentation device having an array of mutually parallel plates with sideways fluid inflow from a feed channel (31,32) extending in the feed direction extending transversely to the plates. A two-dimensional array (40) of flow channel elements (41) extends below the parallel plates to prevent the inflowing fluid from entering between the plates along the plates lower edge while allowing settling sludge to freely settle downward into an agglomeration zone. Formation of a sludge blanket below the plates is prevented and interference of the inflowing fluid with settling slugdge is reduced, enabling a higher throughput of the device.

LC 2010001

This patent has been granted regardless of the attached result of the prior art research and written opinion. The patent corresponds to the documents originally filed.

Sedimentation device having an inflow distributor element

Field of the invention

The invention relates to a sedimentation device comprising:

a number of mutually parallel, spaced-apart inclined plates having side edges extending at an angle to a height direction and an upper and a lower transverse edge extending in a width direction, two sidewalls extending along respective sets of side edges of the plates in a feed direction, transversely to a plane of the plates, and connected to the respective side edges,

A feed channel extending in the feed direction, along at least one side wall, one side of the feed channel being formed by this side wall, a feed opening in the feed channel being situated in the side wall near the lower transverse edge of the plates , for supplying fluid from the feed opening between two adjacent plates, for traveling upwards between the plates to an outflow zone near an upper transverse edge of the plates while settleable material travels along one or more plates in a downward direction to an agglomeration zone below the lower transverse edges of the plates.

Background of the invention

Such a sedimentation device is known from US patent no. 3,706,384 showing a boxshaped tank in which a pack of inclined lamellae is placed. A sludge hopper forms the lower part of the housing for collecting sludge that travels downwards along the plates when water containing settleable material travels upwards along the plates to an effluent collection channel at the plate's upper edges. The lamellae are joined to vertical side walls. On the outside of the each of the side walls a distributing box is provided with a bottom that is level with the lower transverse edge of the lamellae. The distributing boxes have a number of inlet opening communicating with the space between pairs of adjacent lamellae. In this way interfering of water with settleable material flowing upward into the space between the lamella and the sludge flowing downward in this space to the agglomeration zone below the lamellae is reduced and throughput is increased.

It was found however, that the inflow rate of fluid between the lameilea at the bottom does not match the outflow rate of effluent at the top and that this causes an additional influx of fluid via the bottom edge of the lamellae, “bypassing” influx from the sides. Hence interference of fluid supplied from the feed channel along the lower transverse edge into the space between adjacent lamellae with the sludge settling into the agglomeration zone below the lower edges of the lamellae remains problematic and reduces throughput of the known sedimentation device. In the feed direction, transversely to the plane of the lamellae, the inflow varies, such that unevenly distributed settling conditions prevail.

In other known counter current gravity driven sedimentation devices using inflow along the bottom edge of the transverse plates, a sludge blanket will form below the lower transverse edges of the lamellae which reduces the load capacity of these known sedimentation devices.

It is hence an object of the invention to provide a sedimentation device in which interference of inflowing fluid with settleable material near the lower transverse edges of the inclined plates is reduced. It is a further object to provide a sedimentation device in which the throughput can be increased. Finally, it is an object of the invention to provide a sedimentation device that can be easily cleaned and serviced.

Summary of the invention

Hereto the sedimentation device according to the invention is characterized in that a two-dimensional array of flow channel elements, substantially extending in the height direction, is arranged near the lower transverse edges of the plates, the array extending in the width direction from near the a side edge towards a central part of the plates and in the feed direction extending a number of inclined plates.

The array of flow channel elements allows the settleable material, such as sludge or organic matter suspended in water, to travel under the influence of gravity downwards between the plates past the lower transverse plate edges towards a collection position. The array of flow channel elements according to the invention was found to deflect the flow of fluid entering into the space between adjacent plates from the feed opening in the feed channel to be restrained to generally along the lower transverse edge of the plates, directly into the space between adjacent plates. The settleable material can freely flow under gravity conditions downward through the flow channel elements. The flow channel elements according to the invention form a flow resistance for fluid flow in the width direction and in the feed direction and were found to prevent the fluid leaving the feed channel from flowing first downwards and sideways into the agglomeration zone and then back upwards through the settling sludge into the space between the plates. By means of the array of flow channel elements invention, formation of a sludge blanked below the inclined plates is prevented and the interference of inflowing fluid feed with the downwardly traveling settleable material is reduced and throughput of the sedimentation device is increased.

The flow channel elements can be formed by tubular elements that are interconnected and that may have circular, rectangular of other cross-sections shapes, or may alternatively for instance be formed by a honeycomb structure. In one embodiment, the flow channel elements comprise a first set of parallel walls extending in the feed direction and a second set of parallel walls extending in the width direction, the two sets of walls intersecting and being mutually connected. Such an “ice cube tray” -like structure can be easily produced, for instance from plastic material by blow molding. Preferably the array of flow channel elements and can form an integral unit that is easily removed and replaced from the housing for cleaning and / or repair.

The sedimentation device according to the invention may have plates having a height H of between 20 cm and 2 m and a width L of between 20 cm and 2m, at a mutual distance of between 4cm and 10 cm. The flow channel elements may have a diameter of between 2 cm and 10 cm and a height of between 0.5 cm and 15 cm.

The plates in the sedimentation device of present invention may be flat, undulating, corrugated with parallel or with opposed corrugations, or have any other suitable shape.

In a sedimentation device according to the invention an outflow channel is situated, parallel to the feed channel and a sludge collection funnel is mounted below the lower edge of the plates. Preferably the device comprises along each set of side edges of the plates a feed channel and an outflow channel.

Brief description of the drawings

An embodiment of a sedimentation device in accordance with the invention, will by way of non-limiting example, be described in detail with reference to the accompanying drawings. In the drawings ”

Fig. 1 shows a schematic cross-sectional side view of a known countercurrent parallel plate sedimentation device,

Fig. 2 shows schematic frontal cross-sectional view of the known device of fig. 1,

Fig. 3 shows a perspective view of a sedimentation device in accordance with the invention comprising a two-dimensional array of flow channel elements,

Fig. 4 shows a frontal cross-sectional view of the device of fig. 3,

Fig. 5 shows a perspective view of the array of flow channel elements forming an integral unit, and

Figs. 6-8 show arrays of flow channel elements of round, triangular and hexagonal cross section.

Detailed description of the invention

Fig. 1 shows a side view of a known sedimentation device 1 comprising a housing 2 containing an array of inclined plates 3, a funnel-shaped agglomeration zone 4 and a outflow channel 5. Fluid containing settleable material, such as raw water containing suspended organic matter, is fed into a feed channel 6, and flows upwards along the inclined plates 3 to an overflow and via the overflow into the outflow channel 5 to be removed from the device. The settleable material, or sludge S, travels downwards along the plates 3 to the agglomeration zone 4 and is removed via a sludge removal line 7 upon opening of a valve 8.

Fig. 2 shows a frontal view of the device of fig. 1, wherein it can be seen that the inclined plates 3 are placed between two side walls 11,12 inside the housing 2. The feed channels 6, 6 'extend along the side walls 11 , 12 and are parallel to outflow channels 5, 5 '. Each feed channel 6.6 'has a feed opening 15.15 near a lower transverse edge 16 of the plates 3. Fluid flowing from the feed openings 15, 15'was found not to travel directly into the space between pairs of adjacent plates 3 along arrow A as indicated, but instead to travel into the agglomeration zone near the lower transverse edges 16 of the plates 3, along the arrow B. In this way, the feed of fluid entering the space between adjacent plates 3 to travel upwards to the outflow channels 5,5 ', interferes with the sludge S traveling downwards along the plates.

Fig. 3 shows a perspective view of a sedimentation device 20 according to the invention, solving the problem of interferenction of the inflowing fluid with the decending settleable matter. A number of inclined plates 21 extends at an angle a to the vertical height direction H, of about 50 degrees. The plates 21 are with side edges 22,23 connected to side walls 24,25, and project near the lower transverse edges 26 past the side walls 24,25. A housing 28 contains the inclined plates 21 and encloses feed channels 31, 32 to which a fluid containing settleable material is supplied from a feed duct 33. The side walls 23, 24 define one side of the feed channels 31, 21 and provide a feed opening 35, 36 near the lower transverse edges 26 of the plates 21. The side walls 23,24 also define together with the housing 28, outflow channels 37,38 near upper transverse edges 39 of the plates 21.

A two-dimensional array 40 of flow channel elements 41 is placed near the lower transverse edges 26 of the plates 21, each flow channel element comprising a channel of rectangular cross-section. The fluid flows from the feed channels 31,32, through the feed opening 35,35 over the array 40 upwards along the plates 21 in the direction indicated by arrow F. The sludge travels downwards along the plates 21 and through the flow channel elements 41 into the sludge connecting space 43, as indicated by the arrow S.

Fig. 5 is a perspective view of an array 40 of 15x 15 rectangular flow channel elements measuring in the flow direction F and in the width direction W for instance 40 cm, and in the height direction H 5 cm. The array comprises a first set of strips 44.45 and a second set of intersecting strips 46.47 defining the flow channel elements 41 and can be formed as an integral unit, for instance by means of injection molding.

Figs. 6-8 show embodiments of two dimensional arrays of flow channel elements of circular, triangular or honey-comb shaped cross section.