WO2004024286A1

WO2004024286A1 - Device for sealing a waste liquor purifying tank

Info

Publication number: WO2004024286A1
Application number: PCT/BE2003/000151
Authority: WO
Inventors: Pierre Yves Andre
Original assignee: COLLINET-ASSAINISSEMENT, en néerlandais: 'COLLINET-WATERZUIVERING'
Priority date: 2002-09-13
Filing date: 2003-09-11
Publication date: 2004-03-25
Also published as: AU2003265747A1; BE1015108A3

Abstract

The invention concerns a device for sealing a waste liquor purifying tank wherein in a first tank filling stage, the pressure in the discharge conduit (2) is lower than that prevailing in the tank (1) and the closure means (5) and the sealing means (12) are in closed position, in a second tank filling stage, the sealing means (12), driven by the driving means (6) moved in upper position by the waste liquor, is in opened position, the pressure being thus balanced between the tank and the discharge conduit, and, in a third tank filling stage, the closure means, driven by the floating means (6) moved in upper position by the waste liquor, is in opened position, the liquor penetrating into the discharge conduit through the intake orifice.

Description

DEVICE FOR SEALING A RESIDUAL LIQUID PURIFICATION TANK

The present invention relates to a device for closing off a tank for purifying residual liquid, in particular water, loaded with substances of lighter density than the liquid, comprising a duct for discharging purified liquid, having an opening inlet facing upwards in a lower part of the tank and an outlet opening situated in an upper part of the tank, in communication with an outlet of the tank, this inlet opening having a first surface, a means of plugging the intake opening, which is movable between a closed position thereof and an open position in which it is kept away from the intake opening, and a float means connected to the means and movable between a low position, in which the plugging means is in said closed position, and a high position in which the plugging means is in said position opening. Such devices have been known for a long time in particular for purifying water loaded with hydrocarbons. These, lighter than water, float and thus form a surface layer of hydrocarbons which becomes increasingly thick. The purified water, located at the bottom of the tank, is evacuated through the evacuation pipe.

When the hydrocarbon layer becomes very thick, it pushes on the heavier density float and it goes back down to the closed position. It is then time to purge the tank. When it is drained, the tank can be filled with liquid again. At the start of filling, while the closure means closes the intake opening, an overpressure is installed in the tank while the evacuation pipe remains in communication with the outside atmosphere. It follows that the pressure exerted by the rise of the liquid in the tank on the float, a pressure which is equal to the volume of water displaced by the float, is not sufficient to take off the compressed plugging means on the opening d 'admission. It follows that after purging it is necessary to manually open the intake opening, possibly with a descent into the tank to do this.

The object of the present invention is to overcome this drawback and to propose a simple and inexpensive device which makes it possible to reopen the intake duct without manual intervention.

This problem is solved, according to the invention, by a sealing device as described at the beginning, this device further comprising a pressure equalization opening which allows communication between the tank and the evacuation duct, this opening pressure equalization having a second area smaller than said first area, a means for closing the pressure equalization opening which is movable between a closed position thereof and an open position in which it is kept away from the pressure equalization opening, and a drive means connected to the shutter means and movable by the liquid between a lower position, in which the shutter means is in said closed position, and an upper position, in which it is in said open position, device in which, at a first stage of filling the tank, the pressure in the pipe t of evacuation is less than that prevailing in the tank and the means and the closure means are in the closed position, at a second stage of filling the tank, the closure means, driven by the drive means moved to the upper position by the residual liquid, is in position d opening, the pressure thus being balanced between the tank and the evacuation pipe, and, at a third stage of filling the tank, the plugging means, driven by the float means moved in the high position by the residual liquid, is in the open position, the liquid entering the exhaust duct through the intake opening. By providing, for the pressure equalization between the tank and the means of evacuation, an opening of small surface compared to that of the opening of admission of purified water, the pressure exerted on its means of obturation is less important than that produced on the plugging means of the intake opening. This allows an easy and automatic opening of the pressure equalization opening and a pressure balancing which will allow the subsequent opening of the intake opening and the efficient commissioning of the tank, without manual intervention.

According to an advantageous embodiment of the invention, the pressure equalization opening is arranged in the means for blocking the intake opening. This embodiment offers the advantage of allowing the production of a device of reduced size.

According to an improved embodiment of the invention, the above-mentioned float means is fixedly connected to the closure means of the pressure equalization opening, as the above-mentioned drive means of the closure means, and the float means is connected to the plugging means of the intake opening so as to allow a limited initial sliding of the float means relative to the plugging means until said second stage of filling the tank. In this way, the same float means allows an upward drive, under the effect of the pressure of the filling liquid, successively of the sealing means, then of the plugging means. This offers the advantage of a very compact embodiment in the volume of the tank.

Other embodiments of the device according to the invention are indicated in the appended claims.

Other details and particularities of the invention will emerge from the description given below, without implied limitation, and with reference to the attached drawings.

Figure 1 shows a sectional view of a tank closure device according to the invention, in the open position.

2 shows a detailed view of the device according to Figure 1, in the closed position. FIG. 3 represents a detailed view of the device according to FIG. 1, in the pressure balancing position.

In the various drawings, identical or analogous elements are designated by the same references.

In the drawings, the purification tank 1 is intended to purify water loaded with lighter density hydrocarbons, these hydrocarbons having for example a density of the order of 0.7 to 0.8.

A discharge pipe 2 is arranged at the bottom of the tank 1. It has an inlet opening 3 oriented upwards and an outlet opening 4 which opens out through an outlet from the tank. This intake opening has an area which is suitable for the flow rate which it is desired to obtain in the exhaust duct 2 and which is therefore relatively large.

In FIG. 1, over the intake opening 3, a plugging disc 5 is kept in suspension, at a distance from this opening, by a float 6, whose density is tared so that it is intermediate to that of water and that of hydrocarbons. It can advantageously be of the order of 0.85 to 0.9. The plugging disc 5 is moved by the float between an open position of the intake opening 3, shown in FIG. 1, and a closed position of the latter, shown in FIGS. 2 and 3.

In the illustrated embodiment, the float 6 is a hollow cylindrical body, for example made of high density polyethylene, which is filled at least partially with water to reach the aforementioned density. It is provided with a central hollow rod 7 which projects upwards and downwards relative to the body of the float.

The hollow rod 7 is guided, during the movement of the float up or down, by a fixed axis 8, arranged vertically, in the example illustrated at the end of a bracket 9 fixed to the discharge pipe 2 This axis is provided with a stop flange 10 which limits the upward movement of the float 6.

In the illustrated embodiment, there is provided, in the center of the stopper plate 5, a pressure equalization opening 11, which, in the open position, allows communication between the tank 1 and the discharge pipe 2 (see figure 3). This pressure equalization opening 11 has an area smaller than that of the intake opening. In the illustrated embodiment, the ratio between the area of the pressure equalization opening 11 and that of the intake opening is of the order of 1/100. A shutter 12 is, in the embodiment, fixed to the lower end of the hollow rod 7, by means of an axis 13 which allows a slight rotation of the shutter 12 around this axis. The shutter 12 can advantageously be made of a plastic or rubbery material and it preferably has a lower end of conical or semi-cylindrical shape which adapts to the opening pressure balancing 11, itself conical in the example illustrated.

In the closed position shown in Figure 2, the shutter closes the pressure balancing opening, while in the positions shown in Figures 1 and 3 it was moved away from the balancing opening of pressure by the float 6 which serves as its drive means.

In the example illustrated, the shutter 12 is provided with a threaded rod 14, which is screwed into a blind hole in the shutter 12 provided at its free end, so as to project downward through the opening pressure equalization 11. A nut 15, of the butterfly type for example, wider than the pressure equalization opening is arranged at the free end of the threaded rod 14. In the closed position shown in the figure 2, this nut is located at a small distance from the bottom of a recess 16 provided in the underside of the stopper plate 5. In the position shown in FIG. 3, the shutter 12 has been driven upwards by the float 6 and the nut 15 rose with it to abut against the bottom of the recess 16. In this position, the pressure balancing opening 11 is open while the intake opening 3 remains closed.

The operation of the closure device according to the invention will now be described in more detail.

In the open position shown in FIG. 1, the tank 1 is filled with water loaded with hydrocarbons and the float 6, under a pressure of water exerted on it equal to the volume of water displaced, has reached its height maximum limited by the stopper 10. This prevents further sliding upward of the hollow rod 7 on the axis 8. The inlet opening 3 and the pressure equalization opening 11 are in the open position and the water located at the bottom of the tank, and therefore purified, since freed of floating oil, can escape through drain 2.

As the tank operates, more and more hydrocarbons accumulate on the surface of the water, forming at a moment a thick layer which reaches the top of the float 6. As the float 6 has a higher density than this layer of hydrocarbons, it gradually descends until the plugging plate 5 is applied to the intake opening, as shown in FIG. 3, then by pushing the shutter 12 into the opening pressure equalizing valve 11, as shown in FIG. 2. In this position, the threaded rod 14 has slid through the opening 11 and the nut 15 is located a short distance from the bottom of the recess 16 of the closure plate 5.

It is then time to purge the tank, which is done in a known manner, not described here.

When the tank is empty, it can be refilled with water.

At the start of filling, the water which enters tank 1 creates an overpressure inside it with respect to the discharge pipe 2, which remains in communication with the outside air. The stopper plate 5 and the shutter 12 are therefore compressed against their respective opening, keeping them closed.

When the water reaches the float, it exerts on it a rising pressure already mentioned. This pressure, which would be insufficient to take off the stopper plate 5 of large area, is quite sufficient to overcome the pressure exerted by the overpressure of the tank on the shutter, given the small area of the balancing opening. pressure. The ratio between the area of the pressure balancing opening and that of the intake opening will therefore depend on the overpressure to be overcome. In the closure device according to the invention, the float can lift the shutter 12, since, during an initial period, the rod 14 can slide freely in the pressure balancing opening 11, between the position illustrated in the figure 2 and that shown in FIG. 3. During this sliding, the pressure balancing opening allows a flow of water in the evacuation duct 2 and a pressure balancing between the tank 1 and the latter.

In the position shown in FIG. 3, the nut 15 abuts on the bottom of the recess 16 of the stopper plate 5, and the float 6 can now drive the stopper plate 5 upwards without having to overcome an overpressure present. in the tank. The device is therefore opened without any manual intervention.

It should be understood that the present invention is in no way limited to the preferred embodiment described above and that many modifications could be made thereto without departing from the scope of the appended claims.

One could for example imagine a pressure equalization opening in the discharge pipe and a separate float for the shutter of this opening.

Claims

1. Device for closing off a purification tank (1) for residual liquid, in particular water, loaded with substances of density l lighter than the liquid, comprising

- a purified liquid discharge pipe (2), having an inlet opening (3) oriented upwards in a lower part of the tank and an outlet opening (4) located in an upper part of the tank, in communication with an outlet of the tank, this opening o of admission having a first area,

- A means for plugging (5) the intake opening (3), which is movable between a closed position thereof and an open position in which it is kept away from the opening of inlet, and 5 - a float means (6) connected to the plugging means (5) and movable between a low position, in which the plugging means is in said closed position, and a high position in which the plugging means is in said open position, 0 characterized in that it further comprises

- a pressure equalization opening (11) which allows communication between the tank (1) and the discharge conduit (2), this pressure equalization opening having a second area less than said first area, 5 - means for closing (12) the pressure equalization opening (11) which is movable between a closed position thereof and an open position in which it is kept away from the opening d 'pressure equalization, and

- a drive means (6) connected to the shutter means (12) and 0 movable by the liquid between a lower position, in which the closure means is in said closed position, and an upper position, in which it is in said open position, and in that, at a first stage of filling the tank, the pressure in the discharge conduit (2) is less than that prevailing in the tank (1) and the closure means (5) and the closure means (12) are in the closed position, at a second stage of filling the tank, the means d the shutter, driven by the drive means moved to the upper position by the residual liquid, is in the open position, the pressure thus being balanced between the tank and the discharge conduit, and, at a third stage of filling with the tank, the stopper means, driven by the float means moved to the high position by the residual liquid, is in the open position, the liquid entering the evacuation duct through the intake opening.

2. Device according to claim 1, characterized in that the pressure equalization opening (11) is arranged in the plugging means (5) of the intake opening (3).

3. Device according to claim 2, characterized in that the above-mentioned float means (6) is fixedly connected to the closure means (12) of the pressure equalization opening (11), as a means above drive of the shutter means, and in that the float means (6) is connected to the plugging means (5) of the intake opening (3) so as to allow a limited initial sliding of the means of the float (6) relative to the closure means (5) until said second stage of filling the tank.

4. Device according to one of claims 2 and 3, characterized in that the float means (6) is a hollow cylindrical body, provided at its center with a hollow rod (7) which slides on an axis (8) which is arranged vertically in a fixed manner in the tank (1) and which carries a stop (10) which limits the movement of the float means upwards.

5. Device according to claim 4, characterized in that the closure means (12) is fixed to the lower end of the hollow rod (7), in that it is provided with a rod (14) which projects axially downward through the pressure equalization opening (11) and in that a stop (15) wider than the pressure equalization opening (11) is arranged at the free end said rod (14), at a distance from the plugging means (5) in the closed position of the latter and from the sealing means.

6. Device according to any one of claims 1 to 5, characterized in that the float means (6) at a density less than that of the residual liquid and greater than the density of the aforementioned substances of lighter density.