GB2218920A - Liquid separator - Google Patents

Abstract

A separator to remove petrol from drainage water comprises a cylindrical setting chamber having a tangential inlet 5, 10 below the liquid level and a centrally located removable and tubular coalescing filter 6. Liquid flows inwards through the filter wall and via space 7 to an outlet duct 4, incorporated in the outer support of the filter, and thence to outlet 11. <IMAGE>

Description

LAMINAR FLOW COALESCING FILTER INTERCEPTOR This invention relates to a laminar flow, oil and petrol/water interceptor with coalescing filter.

There are two main types of petrol/oil interceptors currently in use on garage forecourts, carparks and industrial premises: A. Full retention 2 or 3 chamber interceptors with dippipes or slots between the chambers.

B. Bypass interceptors where 10% or 20% of the flow is passed through the interceptor chamber and the remainder is passed straight to the outlet pipe.

Both types of interceptor will generally separate the oil and petrol put down to a level of approximately 100 mg/l under general conditions. But no manufacturer is able or prepared to guarantee this level of separation.

The main problem with full retention interceptors is the re-entrainment of separated hydrocarbons during high(storm) flows.

The Bypass interceptor prevents re-entrainment during storm conditions, but it achieves this objective by passing the storm water together with any pollutants straight through the interceptor to the outlet drain.

Thus, both types are liable to allow pollution to occur.

The Laminar Flow, Coalescing Filter Interceptor however, will give dramatically improved levels of oil/water separation.

According to the present invention there is provided a vertical cylinder with the inlet pipe entering the tank via a flow guiding and suppressing chamber which releases the inflow tangentially to the main cylindrical chamber and below the normal liquid level with a coalescing filter mounted on a removable former positioned in the centre of the main chamber.

The outlet pipe is attached to a duct on the side of the outer filter former, which conducts the outflow from the base of the inner filter chamber after the flow has passed through the coalescing filter.

A specific embodiment of the invention will now be described with reference to the accompanying drawings in which figure 1 shows the interceptor with the filter and former in position and figure 2 shows the filter and former removed from the interceptor.

The interceptor comprises an inlet flow guiding and suppression chamber(1) with the inlet pipe(10) attached.

The inlet chamber(l) is attached to the main interceptor chamber(2) and ensures that the incoming flow is directed tangentially to the main cylindrical chamber(2) through orifice(5) which is well below the surface level of the liquid.

In the centre of the main chamber(2) is a vertical cylindrical former(13) with clear holes covering a minimum of 50% of it's area thus allowing free passage of liquid through the outer former(13) to the filter material(6).

The coalescing filter(6) is attached to an inner former which is cylindrical in shape except for one portion of it's circumference where a chord to the circle forms an outlet duct(4) to which the outlet pipe(11) is attached.

At the base of the coalescing filter(6) is the outlet collection chamber (7) which is connected to both the area inside the filter(6)(via holes(9)) and to the outlet duct(4). At the top of the main chamber(2) is an access turret(13) with a socket connection(12) for a separate vent pipe.

The Laminar Flow, Coalescing Filter Interceptor will operate in the following manner: Water and hydrocarbons will enter the inlet flow guiding and suppression chamber(1) where the flow will be directed tangentially to the main cylindrical chamber(2) and approximately midway between the liquid surface and the base of the chamber. In this way a smooth laminar flow is induced which encourages the droplets of oil and petrol to separate out from the water and rise to the surface of the chamber.

In order to pass out of the interceptor, all of the flow must pass through the coalescing filter(6). Very small droplets of oil and petrol do not rise to the surface fast enough to be separated out in the normal timespan allowed in a conventional interceptor, the coalescing filter(6), however, causes these small droplets to join together and form droplets which are large enough to rise to the surface of the chamber.

After the flow has passed through the coalescing filter, the liquid is drawn out from the base of the centre of the inner chamber(3) into the outlet collection chamber(7) then into the outlet duct(4) and then out of the interceptor through the outlet pipe(11).

The base of the inner chamber(3) together with the coalescing filter(6) and the inner former(14) are removable for cleaning or replacement.

Claims (7)

1. An oil petrol interceptor comprising a vertical cylinder with the inlet pipe entering the tank via a flow guiding and suppressing chamber which releases the inflow tangentially to the main cylindrical chamber and below the normal liquid level with a coalescing filter mounted on a removable former positioned in the centre of the main chamber.

2. An interceptor with a coalescing filter mounted such that all the outflow must pass through it.

3. An interceptor with a coalescing filter mounted so as to be removable from the chamber for cleaning or replacement.

4. An interceptor with a coalescing filter mounted on a former.

5. An interceptor as claimed in claim 1 wherein the outlet pipe is attached to a duct on the side of the outer filter former, which conducts the outflow from the base of the inner filter chamber after the flow has passed through the coalescing filter.

6. An interceptor as claimed in claim 1 wherein the coalescing filter is a near-vertical tube, positioned close to the centre of the main interceptor chamber.

7. An interceptor substantially as described herein and with reference to the accompanying drawings (figs 1 & )