GB2042917A

GB2042917A - Oil Separator

Info

Publication number: GB2042917A
Application number: GB8002869A
Authority: GB
Original assignee: ENGEBRETSEN MORTEN AS
Current assignee: ENGEBRETSEN MORTEN AS
Priority date: 1979-02-23
Filing date: 1980-01-28
Publication date: 1980-10-01
Also published as: DE3002511A1; FI800354A; SE8001141L; NO142904C; NO142904B; NO790625L

Abstract

Oil and sludge are separated from contaminated water in a settling vessel divided into two concentric chambers (4, 5) through which the water flows in succession. In one embodiment, the inner chamber (4) is a sludge depository, and the outer chamber (5), which is annular in shape, collects the oil. A flow connection (17) allows water to overflow from chamber (4) into chamber (5) on one side of a radical wall (6), which constrains the water to flow round chamber (5) to underflow outlet (9, 21). An oil-level alarm (22) and manhole (10) are provided. <IMAGE>

Description

SPECIFICATION Oil Separator The present invention relates to oil separators, which are used to separate oil from waste water where such treatment of waste water is necessary, especially in service stations, work shops and the like.

Over the years, many different versions of oil separators have seen the light of day. The simplest form is a container or tank in which waste water is allowed to remain for a certain length of time such that sludge will sink to the bottom and oil rise to the top, forming a layer on the surface. Water and oil can then be tapped off from different levels of the container, but a substantial drawback of this embodiment is that the introduction of additional amounts of waste water disturbs the mass of water and can cause already-separated oil and water to become remixed.For this reason, more advanced oil separators have been developed, which can be divided into two main types: separators in which the tank or container is cylindrical and lies prone, i.e., with the axis of the cylinder approximately horizontal, and upright, cylindrical oil separators in which the axis of the cylinder is vertical. Upright cylindrical oil separators are preferable for a number of applications, among other reasons because they are easier to install and provide better possibilities for maintenance, inspection and cleaning, and they are also simpler to empty of sludge and oil than horizontal cylindrical separators.

In relation to the space they occupy, upright cylindrical oil separators are also able to treat larger amounts of liquid per unit of time than horizontal cylindrical oil separators occupying the same space.

The primary object of the present invention is to improve the water-oil separating ability of upright oil separators such that the waste water will be cleaner than previously, and a second object is to increase the throughflow velocity without adverse effect on the separator's ability to separate water and oil.

In accordance with the invention, these objects are obtained by making the course or path that the waste water is forced to follow be as long as possible within the space that is available, because the longer the time a water/oil mixture is permitted to flow in a quiet stream, the greater the possibilities for the oil to rise to the top and sludge and water to sink down relative to one another.

In the present invention, therefore, the waste water is made to flow in a quiet stream as near to the periphery of the upright cylindrical oil separator as possible, such that the flow path will obtain a maximum length within the space that is available.

The invention is characterized by the features disclosed in the appurtenant patent claims, and will be elucidated further in the following with reference to the accompanying drawings, where Figure 1 is a-vertical cross section through one embodiment of an oil separator according to the invention, Figure 2 shows a horizontal cross-section, and Figure 3 shows, in perspective, a cross section through an embodiment.

As depicted in the drawings, the oil separator comprises a cylindrical tank 1 with a conical top portion 2. Disposed inside the cylindrical tank 1 is a circular wall 3 which is concentric with the outer tank wall, thus forming an inner chamber 4 and an outer, annular chamber 5. The chamber 5 is ring-shaped, then, and is closed by a wall 6. An inlet 7 leads from the outside and into the inner chamber 4, and communication is then provided via a flow connection 8 from the inner chamber to the annular chamber, through which the liquid that is to be treated passes in an even flow toward an outlet 9. The flow path and the various components will be described in greater detail below, with reference to Figure 3.

The top 2 of the tank has a manhole 10; beneath this is a ladder 1 1 and a platform 12 upon which one can stand during inspection, maintenance and cleaning.

The flow path is shown most clearly on Figure 3, where the liquid to be treated flows in as indicated by the arrows. At the inlet to the inner chamber 4, the liquid encounters a flow baffle 13 which deflects the liquid such that it flows downwards. On Figure 1 , the inlet pipe 7 is bent downwards at 14 for the same purpose. Inside the chamber 4, the sludge in the liquid being treated has time to sink down to the bottom and will collect there. The chamber 4 is emptied of sludge at regular intervals. The chamber 4 will gradually become filled with liquid, and when the level of the liquid reaches a certain height, it will flow over an overflow edge 15 of a compartment 16 which surrounds a through-flow connection 17 leading into the outer annular chamber 5. The compartment 16 is provided with a sieve 18 at the top.The flow connection 17 has the form of a pipe, as best seen on Figure 2, and this pipe leads the liquid, which is still mixed with oil, out toward the outer periphery of the annular chamber. Inside the chamber 5, the liquid flows quietly and oil has time to rise up to the surface of the water, floating on top of the water. Flow distributor baffles 1 9, disposed radially, can be placed in the annular chamber 5 to direct the flow. Gradually, as the outer annular chamber 5 becomes filled, the plane of separation between the oil and water in the chamber will rise, and after the plane of separation has risen to a level that is higher than an outer edge 20 at the intake to the outlet 9, the oil separator is in operation.As the plane of separation continues to rise, only water will enter at the intake and flow up through the outlet 9 which is connected to a discharge pipe 21, and the oil will collect in the annular chamber 5, floating on top of the mass of water. Before the layer of oil becomes so thick that the plane of separation for the water and oil sinks below the edge 20, the oil must be emptied.

A sensor 22 for an alarm system which warns one if the level of liquid in the chamber becomes too high and the layer of oil to thick is disposed in the vicinity of the outlet 9.

The example illustrated herein serves only to illustrate the invention and should not be construed as restricting the protection provided by this patent, as other embodiments can easily be imagined which would lie within the scope of the invention. For example, the outer annular chamber might well operate as a sludge depository and oil separator, if desired, with oil being collected in the inner cylindrical chamber, but the method of operation would be the same, and such embodiments also lie within the scope of the invention.

Claims

1. An oil separator, comprising an upright, substantially cylindrical tank, wherein the tank has two concentric chambers comprising an innet chamber and an outer chamber which is annular in shape, one chamber being a sludge depository and the other being an oil separator, and there being provided a flow connection between the two chambers and an outlet from the separator portion.

2. An oil separator according to Claim 1, wherein the annular chamber is closed off by an upright, transverse partition, and the flow connection between the inner and annular chambers and the outlet, which is from the annular chamber, are located on respective sides of said partition.

3. An oil separator according to Claim 1 or Claim 2, wherein the inlet to the sludge depository is formed so to direct, in use, a flow of liquid to be treated downwards.

4. An oil separator according to Claim 3, wherein the stream of liquid has flow distributors on the inlet side.

5. An oil separator according to any preceding claim, which has an outlet box with at least two water-overflow slots.

6. An oil separator according to any preceding claim, wherein the flow connection between the sludge depository and the outer annular chamber comprises a closed compartment with an overflow edge, one wall of said compartment being the wall between the two chambers, and wherein the flow connection is formed by an opening in said wall, said opening lying at a lower elevation than the inlet.

7. An oil separator according to any preceding claim, wherein one or more upright, radial flow distributor baffles are provided in the annular chamber.

8. An oil separator according to any preceding claim, wherein said outlet has a liquid intake which lies lower than the calculated lowest level of the plane of separation for oil and water.

9. An oil separator according to any one or more of the preceding claims, which has an outlet box on which a plate is mounted which, together with a rearwardly-directed outlet pipe, ensures that liquids which flow out, in use, will be taken from the back wall of the separator portion.

10. An oil separator substantially as hereinbefore described with reference to, and as illustrated in, the accompanying drawings.