WO2015128769A1

WO2015128769A1 - A separator for separating a heavier liquid from a lighter liquid

Info

Publication number: WO2015128769A1
Application number: PCT/IB2015/051084
Authority: WO
Inventors: John Edgar Scragg
Original assignee: Individual
Current assignee: Individual
Priority date: 2014-02-13
Filing date: 2015-02-13
Publication date: 2015-09-03
Anticipated expiration: 2016-08-13
Also published as: GB2538904A; ZA201606216B; GB201615217D0

Abstract

A separator (10) for separating a heavier liquid from a lighter liquid that floats on the heavier liquid is disclosed. Mixed liquids enter the separator through an inlet (18). There is an outlet (22) for the lighter liquid and an outlet (24) for the heavier liquid. There is also a float (28) which floats on the heavier liquid and sinks in the lighter liquid. A closure elements (52) shuts-off the outlet (24) until the float (28) is lifted by an accumulation of heavier liquid. A guide rod (46) is connected to the float so that it moves with it. A diaphragm (32) is subjected on one side to atmospheric pressure and on the other side to the pressure in the separator. The diaphragm, when the pressure in the separator is below atmospheric, hold the rod and float in a position in which the element (52) closes off the outlet (24). A backing plate (34) is provided against which the diaphragm (32) is pressed when the pressure in the separator is at or above atmospheric pressure. The backing plate (34) has an opening in it which exposes the diaphragm to atmospheric pressure.

Description

A SEPARATOR FOR SEPARATING A HEAVIER LIQUID FROM A LIGHTER LIQUID

FIELD OF THE INVENTION

THIS INVENTION relates to a separator for separating a heavier liquid from a lighter liquid.

BACKGROUND TO THE INVENTION

The problem of water contamination of diesel fuel is well known. Diesel engines thus require a separator for removing water from diesel fuel that is being pumped to the engine. Separators which are intended to remove water from diesel and other fuels rely on the difference between the specific gravity of the water and the specific gravity of the fuel for the purposes of separation. The water is allowed to collect in the bottom of a receptacle and is drained-off periodically. In most constructions of which the Applicant is aware, the water is drained off manually. The separator includes a transparent bowl and the engine operator is able, by visual inspection, to see how much water has accumulated. By opening a tap he can permit the accumulated water to run out. The tap is manually closed just before fuel starts to drain out. Buzzers and warning lights are sometimes used to warn the engine operator of a water build-up in the separator.

The Applicant is also aware of separators which include means for automatically discharging accumulated water. Such separators must be fitted on the pressure side of a lift pump. Many engine layouts include such a pump which draws fuel from the tank and feeds it to the fuel injection system. Once a sufficient quantity of water has accumulated, a float lifts a valve closure member off a seat thereby to open a drain outlet. If the fuel feed pump is running at the time, then the pressure in the separator assists in discharging the accumulated water. If the pump is not running then water merely flows out under the effects of gravity. The separators with automatic water discharge of which the Applicant is aware cannot be used on the suction side of the pump. This is because, if the drain outlet opens whilst the pump is running, water will not be discharged but air will be drawn in. Air, and probably also entrained water, will consequently reach the engine, possibly causing damage but certainly causing it to run unevenly or stall.

In layouts with a lift pump, it is possible to use manually drained separators on the pressure side or suction side of the pump. In other layouts there are no lift pumps, and hence no pressure side at which a separator can be fitted. When a manually operated separator is used on the suction side, it must not be opened whilst the engine is running.

Even when a separator is fitted on the pressure side, and hence there can be automatic water discharge, there is a problem in that if the fuel has water in it, the mixture is emulsified in the pump. When the emulsion subsequently passes through the separator, water from fuel separation is less efficient because of the physical state of the liquids.

For all these reasons separators on the suction side of the pump are most common and can be fitted more readily, but cannot include automatic discharge of accumulated water. In my South African Patent Specification No. 95/8579 there is disclosed a separator capable of operating on the suction side of the fuel pump, and having means for automatically dumping water that has accumulated. This separator has a number of advantages over a separator without such a facility. One such advantage is that, by dumping water automatically, it relieves the operator of the engine of all responsibility. If he forgets to drain a separator without automatic water dumping, water can be carried over to the engine. A unit that drains automatically prevents this happening even if the driver is neglectful. Furthermore, separation occurs before the lift pump (if one is provided) and fuel / water emulsification at the pump is avoided.

OBJECT OF THE INVENTION The main object of the present invention is to improve the separator of South African Patent Specification No. 95/8579.

BRIEF DESCRIPTION OF THE INVENTION

According to the present invention there is provided a separator for separating a heavier liquid from a lighter liquid that floats on the heavier liquid, the separator comprising a casing having an inlet for a mixture of lighter and heavier liquids, a first outlet for the lighter liquid and a second outlet for the heavier liquid, the second outlet being at the lower end of said casing so that the heavier liquid which has accumulated in the lower part of said casing can be discharged therethrough, a float structure including a float which floats on the heavier liquid and sinks in the lighter liquid, first closure means which shuts-off said second outlet until the float is lifted by an accumulation of heavier liquid in said casing, the float structure further including a member which is connected to said float so that it moves therewith and the separator further including a diaphragm which is subjected on one side thereof to atmospheric pressure and on the other side thereof to the pressure in said casing, the diaphragm, when the pressure in said casing is below atmospheric, holding said member and said float in a position in which said first closure means closes off said second outlet; characterized in that a backing plate is provided against which the diaphragm is pressed when the pressure in the casing is at or above atmospheric pressure, the backing plate having an opening therein which exposes said one side of the diaphragm to atmospheric pressure. The diaphragm can have a relaxed state and a deformed state, the diaphragm being in its relaxed state when against said backing plate and in its deformed state when the pressure in the casing is below atmospheric.

Spring means can be provided for pushing the diaphragm against the backing plate.

The portion of the diaphragm which seals said opening is preferably thicker than other parts of the diaphragm. In the preferred embodiment said backing plate is in the form of a dome with said opening in the centre of the dome, and the diaphragm has its periphery secured to the backing plate at a location remote from said opening. It is the portion of the diaphragm which presses on the centre of the dome to close said opening which is thicker than the portion that presses on the remainder of the dome.

The opening in the backing plate can be encircled by a valve seat, and a valve closure element protruding from the diaphragm can be provided which enters said opening and makes sealing contact with the valve seat upon the pressure in the casing being above atmospheric.

Said closure element can be conical and is preferably moulded integrally with the diaphragm. BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the present invention, and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings in which;

Figure 1 illustrates a separator and storage tank combination; and

Figure 2 illustrates a detail of a modified form of the combination of Figure 1 . DETAILED DESCRIPTION OF THE DRAWING

Referring to Figure 1 of the drawings, the separator illustrated is generally designated 10 and comprises a casing 12. The fuel storage tank is generally designated 14. The separator 10 and the tank 14 are connected by a main flow line in the form of a pipe 16. The entrance to the pipe 16 is close to the bottom of the tank 14 and the exit from the pipe 16 is at the inlet 18 to the casing 12 of the separator 10. There is a deflector plate 20 across the inlet 18, the plate 20 deflecting incoming liquid down towards the bottom of the casing 12. The casing 12 has an outlet 22 close to the upper end thereof for lighter liquid designated L2 and an outlet 24 at the lower end thereof for heavier liquid designated L1 . The suction side of a pump (not shown) is connected to the outlet 22. Reference numeral 26 designates a float structure which includes a float 28 which floats on the heavier liquid L1 but sinks in the lighter liquid L2. It will be noted that the heavier liquid L1 accumulates at the lower end of the casing 12 and the lighter liquid L2 floats on the heavier liquid L1 . The float structure 26 further includes a member 30 which is attached at its lower end to the float 28. The upper end of the member 30 is in contact with, but is not attached to, a diaphragm 32.

The diaphragm 32 is located adjacent a backing plate 34 which is manufactured from a synthetic plastics material. The backing plate 34 has an opening 36 in it encircled by a valve seat 38. On the opposite side of the backing plate 34 to the diaphragm 32 there is a chamber 40. A breather pipe 42 leads from the chamber 40 to atmosphere. The upper surface of the diaphragm 32 is thus subjected, through the opening 36, to atmospheric pressure whilst the lower surface thereof is subject to the pressure within the casing 12. When the fuel pump is switched off the opening 36 is closed by the upper surface of the diaphragm 32. This is as a result of any internal pressure within the casing 12 and the memory of the diaphragm 32. This position of the diaphragm 32 is shown as the solid line in Figure 1 . A spring or springs (not shown) can be used to urge the diaphragm 32 against the backing plate 34.

The surface of the backing plate 34 limits upward movement of the diaphragm 32. Furthermore, the backing plate 34 reduces the risk of failure of the diaphragm 32 by preventing the diaphragm 32 from being unnecessarily stretched in the event of the internal pressure inside the casing 12 becoming positive, either as a result of positive pump pressure or as a result of the fuel tank being located above the separator 10 to provide a head.

Within the casing 12 there is a sub-housing 44. A guide rod 46 extends down from the float 28 into the sub-housing 44 and ensures that the float 26 moves along a vertical line. The outlet 24 communicates by way of a passage 48 with the interior of the sub- housing 44. A valve seat 50 encircles the entrance to the passage 48 and closure means in the form of a valve closure element 52 co-operates with the seat 50 to provide an outlet valve. A pin 54 is fixed to the valve closure element 52 and extends upwardly through the top wall of the sub-housing 44. The guide rod 46 and the pin 54 are connected to a cross member 56. More specifically the member 56 is connected to the rod 46 so that its left hand end lifts and drops with the rod 46. Some sliding action is permitted between the rod 46 and the member 56 so that the rod 46 is not pulled off a vertical line by the member 56 when it pivots. At the end thereof remote from the rod 46 the member 56 is pivotally mounted on the sub- housing 44.

The holes in the top wall of the sub-housing 44 through which the guide rod 46 and the pin 54 pass are slightly oversized.

The member 56 passes through a slightly oversized transverse hole in the pin 54. The member 56 thus displaces the pin 54 vertically as it lifts and drops whilst the slight freedom of movement of the member 56 in the hole of the pin 54 prevents skewing of the pin 54 off its vertical line by the pivoting member 56. The member 56 provides a mechanical advantage so that the pin 54 and closure element 52 have a force exerted on them which is sufficient to lift the element 52 clear of the seat to open the outlet valve and to hold the element 52 against the seat 50 to close the outlet valve. A subsidiary flow line in the form of a pipe 58 leads from the bottom of the tank 14 to the bottom of the separator 10. It is possible for the pipe 58 to be open at all times or alternatively or can be opened automatically when the level of heavy liquid that has accumulated in the tank 14 exceeds a predetermined level. The exit from the pipe 58 is above the level of the interface I between the heavy liquid L1 and the lighter liquid L2 and is below a baffle 60.

The tank 14 will normally contain fuel and it is well known that fuel becomes contaminated with water. Because the specific gravity of water is greater than that of the fuel the two liquids tend to separate and the fuel tends to float on the water. The outlet 22 is connected to a fuel pump (not shown) which feeds fuel to the engine which is to use the fuel stored in the tank 14. On the assumption that the fuel pump is switched off, the pressure in the casing 12 is atmospheric or above, depending on the difference between the level in the tank 14 and the level of the interface I. If sufficient water has collected in the lower part of the casing 12, the float 28 lifts carrying the rod 46, cross member 56 and pin 54 up with it. The valve closure element 52 thus lifts off the seat 50 and water flows through the outlet 24 until such time as the float 28 drops to a position in which the element 52 bears down on the valve seat 50.

When the fuel pump is switched on, fuel is drawn through the pipe 16 and inlet 18 to the interior of the casing 12 and then to the outlet 22. Because the separator 10 is connected on the suction side of the pump, the pressure within the casing 12 drops to sub-atmospheric. Lifting of the valve closure element 52 in these circumstances would result in air being drawn through the outlet 24 and being fed to the engine, resulting in fuel starvation and possible stalling. As stated, when the fuel pump is running, the pressure within the casing 12 is below atmospheric and the underside of the diaphragm 32 is subjected to this pressure. Atmospheric pressure is acting on the top surface of the diaphragm 32 so that it assumes the position shown by the dotted line in Figure 1 . In this position, the diaphragm 32 holds the member 30 and hence the float 28 in their lowermost positions. The valve closure element 52 thus remains on the valve seat 50. When the engine is switched off the pressure within the casing 12 rises to atmospheric and the diaphragm 32 moves to the position shown by the solid line in Figure 1 . The downward force that was exerted on the member 30 and float 28 is thus removed and, if water has collected in the lower part of the casing 12 in sufficient volume to lift the float 28, then the float 28 lifts at this time and permits water to flow out of the separator 10 through outlet 24. It will be understood that once water has been discharged the float 28 moves down again to close off the outlet 24. The fact that the member 30 and the diaphragm 32 are not connected means that the diaphragm 32 does not restrict this downward movement. The function of the diaphragm 32, therefore, is simply to ensure that, when there is a sub-atmospheric pressure in the casing 12, the float 28 cannot lift.

The capacity of the casing 12 is such that, during normal operation, the quantity of water that collects will never be such that it will be carried out of the outlet 22. As engines are generally run intermittently, discharge of water will invariably occur before there is any danger of it being carried over into the fuel pump and hence to the engine. As a result of the oversized holes in the top wall of the sub-housing 44, there are annular gaps between the top wall of the sub-housing 44 on the one hand and the guide rod 46 and pin 54 on the other hand. These gaps are such that water can enter the sub-housing 44 but solid particles in the fuel are prevented from reaching the interior of the sub-housing 44 and hence the valve seat 50. Such particles, if they lodge between the valve seat 50 and the valve closure element 52, can prevent the outlet 24 being closed off properly.

In the event of diaphragm failure, the diaphragm's "memory" or the spring (or springs) provided ensures that the diaphragm 32 seals on the valve seat 38, thus preventing fuel leakage from the casing 12 via the breather pipe 42. In this situation, the only part of the diaphragm 32 that is exposed to atmospheric pressure is one side of the portion that spans across the valve seat 38.

Turning now to Figure 2 this illustrates a modified form of diaphragm and also illustrates the mounting of the diaphragm.

The diaphragm of Figure 2 is designated 62 and is moulded so as to have a main part with a thinner wall than that of a minor part. The diaphragm 62 is in the form of a dome. Its edge zone is between the flange 64 of a closure plate 66 and a peripheral part 68 of the backing plate designated 70. The backing plate 70 is also in the form of a dome with the opening 36 in the centre of the dome.

The thicker walled part of the diaphragm 62 is in the form of a disc 72 which is moulded integrally with a cone 74. A strengthening plate 76 is secured, either by welding or by means of a number of bolts, to the backing plate 70. The opening 36 is in the plate 76 and the valve seat 38 encircles the opening 36. The cone 74 enters the opening 36 and contacts the valve seat 38 when the pressure in the casing 12 is above atmospheric. The member which is equivalent to the member 30 is designated 78.

The "memory" of the rubber, or rubber-like material, of the diaphragm tends to return the diaphragm to the full line positon shown in Figure 2.

The thick walled disc 72 ensures that the outlet remains closed even if the thinner walled part of the diaphragm is ruptured.

Claims

CLAIMS: 1 . A separator for separating a heavier liquid from a lighter liquid that floats on the heavier liquid, the separator comprising a casing having an inlet for a mixture of lighter and heavier liquids, a first outlet for the lighter liquid and a second outlet for the heavier liquid, the second outlet being at the lower end of said casing so that the heavier liquid which has accumulated in the lower part of said casing can be discharged therethrough, a float structure including a float which floats on the heavier liquid and sinks in the lighter liquid, first closure means which shuts-off said second outlet until the float is lifted by an accumulation of heavier liquid in said casing, the float structure further including a member which is connected to said float so that it moves therewith and the separator further including a diaphragm which is subjected on one side thereof to atmospheric pressure and on the other side thereof to the pressure in said casing, the diaphragm, when the pressure in said casing is below atmospheric, holding said member and said float in a position in which said first closure means closes off said second outlet; characterized in that a backing plate is provided against which the diaphragm is pressed when the pressure in the casing is at or above atmospheric pressure, the backing plate having an opening therein which exposes said one side of the diaphragm to atmospheric pressure said diaphragm sealing said opening whilst it is pressed against the backing plate.

2. A separator as claimed in claim 1 , wherein the diaphragm has a relaxed state and a deformed state, the diaphragm being in its relaxed state when against said backing plate and in its deformed state when the pressure in the casing is below atmospheric.

3. A separator as claimed in claim 1 or 2, and including spring means for pushing the diaphragm against the backing plate.

4. A separator as claimed in claim 1 , 2 or 3, wherein the portion of the diaphragm which seals said opening is thicker than other parts of the diaphragm.

5. A separator as claimed in any one of claims 1 to 4, wherein said backing plate is in the form of a dome with said opening in the centre of the dome and the diaphragm has its periphery secured to the backing plate at a location remote from said opening.

6. A separator as claimed in claim 5, when dependent on claim 4, wherein the portion of the diaphragm which presses on the centre of the dome to close said opening is thicker than the portion that presses on the remainder of the dome.

7. A separator as claimed in any preceding claim, wherein said opening is encircled by a valve seat, and a valve closure element protruding from the diaphragm is provided which enters said opening and makes sealing contact with the valve seat upon the pressure in the casing being above atmospheric.

8. A separator as claimed in claim 7, wherein said closure element is conical.

9. A separator as claimed in claim 7 or 8, wherein said closure element is moulded integrally with the diaphragm.