AU777266B2 - Improvements in separators for waste water and other liquids - Google Patents

Description

J, AUSTRALIA ,L.

PATENTS ACT 1990 COMPLETE SPECIFICATION FOR OFFICE USE Short Title: Int. CI: Application Number: Lodged: Complete Specification-Lodged: Accepted: Lapsed: Published: Priority: PQ6866 dated 12 April, 2000 Related Art: Name of Applicant: Address of Applicant: Actual Inventor: Address for Service: TO BE COMPLETED BY APPLICANT SEPA Waste Water Treatment Pty. Ltd.

13 Gawarra Road, CARINGBAI- NSW 2229 c- Aac-00ULiYs AC"co i -JCJ areer/ Mcu 1 Ha4C 2-3za Roger Andrew Minshull ANDERSON-TAYLOR ASSOCIATES, Registered Patent Attorneys of 10 Harrison Avenue BONNET BAY N.S.W. 2226 Complete Specification for the invention entitled: IMPROVEMENTS IN SEPARATORS FOR WASTE WATER AND OTHER LIQUIDS The following statement is a full description of this invention, including the best method of performing it known to me: This invention relates to separators for use with mixtures of liquids and/or suspended solids in liquids. More particularly although not exclusively it discloses an improved apparatus for separating out oil or suspended solids from waste water.

With the applicant's existing Australian patent 715076 a separator is disclosed which in a position of use has first and second fixed plate packs arranged within a tank at an acute angle to the vertical. In use of the separator the plates are submerged and a laminar flow of an oil/water "mixture passes downward through the first plate pack and upward through the second plate pack. The lighter oil component of the mixture separates out and is drained away by an exit weir above the plates. The heavier water component is discharged separately through a lower outlet. While the apparatus described in patent 715076 works well at treatment rates of less than about 5000 litres/hour it becomes inefficient at higher flow rates. Above about 5000 litres/hour the downflow velocity in the vicinity of the water outlet is too high relative to the rise rate of the minute oil droplets still remaining in the mixture. These oil droplets are therefore entrapped and carried into the water outlet. There are additional problems with cleaning the plates of prior art separators. Solid particles settle out as the mixture passes through the plate packs and a certain proportion cling to the plate surfaces. Over time this buildup disrupts the flow. With prior art separators the plates are not readily removed and have to be cleaned in situ.

It is therefore an object of this invention to ameliorate the aforementioned disadvantages and accordingly an apparatus is disclosed for separating out a first liquid component from a mixture formed with a second heavier liquid component, said apparatus in a position of use including a plurality of plate packs arranged within a tank and inclined to the vertical, means for introducing from an inlet a substantially laminar flow of said mixture downward through a first of said plate S•packs, upward through a second of said plate packs and .downward through a third of said plate packs whereby in operation of said apparatus the plates are submerged and during flow through said plate packs said first liquid oo o i component substantially separates out toward a location above said plate packs, first outlet means above said plate packs for drainage of said first liquid component from said tank and a second lower outlet means located downstream of the o *third of said plate packs for drainage of said second liquid component from said tank.

Preferably said plate packs are adapted to be readily removed from said tank for maintenance.

It is further preferred that said first outlet means be located clear of the plate packs to facilitate removal of said packs.

It is further preferred that plates comprising said packs are arranged at and angle of between about 15 degrees and degrees to the vertical.

Currently preferred embodiments of the invention will now be described with reference to the attached drawings in which: Figure 1 Figure 2 Figure 3 Figure 4 is a cross-sectional side elevation of a first embodiment of an oil/water separator according to this concept, is a plan view of the separator of figure 1, is a cross-sectional side elevation of a second embodiment of an oil/water separator, and is a plan view of the separator of figure 3.

Referring first to figures 1 and 2 the separator may comprise first, second and third packs of spaced apart parallel plates. These are numbered 1, 2 and 3 respectively. They are arranged across the interior width of an elongatecd tank 4 and with this embodiment are preferably inclined at an angle of about 45 degrees to the vertical. There is also an oil/water mixture inlet 5 at one end of the tank and a waste water outlet 6 at the other end. Although not shown in the drawings each pack may comprise a set of 70 plates arranged in parallel and spaced at 10 mm. Above the plate packs and toward each end of the tank are oil collection weirs 7 and 8 which extend transversely across the width of said tank.

-4- There are also a number of flow directing baffles in the tank. These extend down in front of the mixture inlet at 9 and 9A, down and horizontally across from the upstream wall of the first plate pack at 10 and 10A, up from the the juncture of the first and second plate packs at 11, down from the juncture of the second and third plate packs at 12 and up from the downstream wall of the third plate pack at 13. With the liquid level in the tank as indicated at 14 these baffles constrict the flow path through the separator to that shown by arrows 15, 16, 17 and 17A. The untreated oil/water mixture S"entering at 5 first encounters the baffles 9 and 9A which oooo•: :.:.:direct the flow downward and reduce turbulence. Any large oil o droplets separating out at this point rise and form a surface layer which is drained by the exit weir 7. The mixture then .oeo.i passes over partition 18 and down in laminar flow through the first plate pack i, up through the second plate pack 2 and **.down through the third plate pack 3. During laminar passage through plate packs 1 and 2 the oil colloidal particles combine into larger droplets. These rise to collect in a layer forming the top of the liquid surface at the upstream and central sections 19, 19A of the tank on each side of baffle 11. Any suspended particles such as sand, grit or the like fall out from the liquid and collect in the bottom compartment 20 formed between the baffles 10 and 12. During passage down through the third plate pack the small residual oil droplets (which with prior art separators are entrapped and carried out in the waste water flow) coalesce into larger droplets on the underside of the plates and then rise to add to the oil layer in the central section 19A of the tank adjacent outlet weir 8. This third plate pack in effect operates to provide additional surface area and reduce the rise rate necessary for these small remaining oil droplets to coalesce and separate out from the water. Substantially oil free water then flows from under the third plate pack and up to the water outlet 6. Preferably this outlet includes a threaded collar or adjustable plates 21 which are height adjustable so that the level 14 of the liquid in the tank is sufficient to cause the accumulated oil layers in the upstream and central sections to spill out through the exit weirs 7 and 8. Although not shown in the drawings separate °o°°.compartments on the side of the tank may be provided to collect the oil from these weirs.

In accordance with this invention the plate packs are removable for maintenance. With this embodiment they are slidably mounted between inclined support rails 22 affixed to each side wall of the tank. There are also transverse beams oooo: 23 on which the bottom of each pack rests. The aforementioned baffle 11 is preferably inclined at the same angle as the plates so as not to impede their slidable insertion or removal along the rails 22. The outlet oil weirs 7 and 8 are also located well clear toward each end of the tank.

With the second embodiment of the invention as shown in figures 3 and 4 the main items which correspond in function to those of figures 1 and 2 are marked by the same numbers but with the addition of an accent In this case the tank 4' is shown mounted on a stand 23A and a hopper 24 is located directly below the plate packs 2' and This hopper collects any solids which settle out of the liquid as it passes through the plates. There is an outlet 25 at the bottom of the hopper for separate removal of these solids.

It will thus be appreciated that this invention at least in the form of the embodiments disclosed provides useful improvements to oil/water separators. Clearly however the oooeo examples described are only the currently preferred forms of this invention and a wide variety of modifications may be made which would be apparent to a person skilled in the art.

For example the shape and configuration of the tank and position of the plate packs therein may be changed according to application. Also, while it is currently preferred to ***construct the apparatus from stainless steel the invention extends to the use of any other suitable material.

For the purposes of this specification expressions such as "down", "vertical", "above", "lower", "over" and "under" etc. refer to the apparatus in a position of use as illustrated in figures 1 or 3 and are not to be read as necessarily limiting.

Claims (5)

1. 3. The apparatus as claimed in claim 1 wherein said first outlet means are located clear of said plate packs and toward an end of the tank.
2. 4. The apparatus as claimed in claim 3 wherein an inlet for said mixture is located at one end of the tank and said second lower outlet means is located at an opposite end of the tank. The apparatus as claimed in claim 1 wherein the undersides of said plate packs rest on transverse beams which extend across between the side walls of said tank.
3. 6. The apparatus as claimed in claim 1 wherein said first outlet means include collection weirs which extend transversely across the width of said tank.
4. 7. The apparatus as claimed in claim 1 wherein a hopper is located below the plate packs to collect any solids which settle out of the mixture as said mixture passes through said •plate packs. d. The apparatus as claimed in claim 1 wherein said first liquid component is oil and said second liquid component is *water.
5. 9. An apparatus for separating out a first liquid component Sliquidfrom a mixture formed with a second heavier liquid component, said apparatus being substantially as described herein with reference to figures 1 and 2 or 3 and 4. Dated this 20th day of May, 2004 SEPA Waste Water Treatment Pty. Ltd. By Our Patent Attorney MICHAEL ANDERSON-TAYLOR C, a a. a a a a *.aa a a. a a a a a 9 a a a a a a. a a. a a.