WO1993008108A1

WO1993008108A1 - Fluid storage and metering device

Info

Publication number: WO1993008108A1
Application number: PCT/AU1992/000567
Authority: WO
Inventors: Jack John Child
Original assignee: Jack John Child
Priority date: 1991-10-24
Filing date: 1992-10-22
Publication date: 1993-04-29

Abstract

A reservoir (2) continuously receives fluids, e.g. sewerage slurry. The fluid normally drains into chamber (4) through valve (6). The other valve (8) of chamber (4) remains closed due to the negative pressure in reservoir (2) and chamber (4) caused by the connection thereof to the suction side of pump (17). In discharge mode, however, the pressure side of pump (17) is connected via line (22) so as to pressurise chamber (4). This results in closing of valve (6) and expulsion of the fluids through nozzle (10). Entry of gas with a batch of fluid (at 3) is registered by vacuum switch (12) which starts a discharge program consisting of a pre-set delay (during which the negative pressure is maintained) followed by a discharge of pre-set duration.

Description

TITLE: "FLUID STORAGE AND METERING DEVICE"

FIELD OF THE INVENTION

The present invention relates to fluid storage and metering devices.

The invention has been developed primarily for use in the storage and transfer of sewerage and other waste slurries and will be described hereinafter with reference to this application. However, it will be appreciated that the invention is not limited to this particular field of use.

BACKGROUND OF THE INVENTION

In the past it has been known to collect waste

. slurries such as sewerage in large purpose built vessels. When it is then desired to transfer the slurry to a treatment plant, for example, the storage tank is pressurised and the fluid or slurry discharged for further processing. In many cases the fluid inlet to the vessel also serves as the fluid outlet.

A major disadvantage with such prior art systems is that the storage vessel itself effectively becomes off-line during the dispensing or discharge cycle and is unable to accept further waste material until the discharge cycle has been completed.

It is an object of the present invention to overcome or at least ameliorate the above disadvantages of the prior art.

DISCLOSURE OF THE INVENTION

According to the invention there is provided a fluid storage and metering device comprising: a reservoir adapted to continuously receive fluids; a dispensing chamber disposed to receive fluid from said reservoir; first normally open valve means connecting said reservoir to said dispensing chamber; second normally closed valve means for intermittently discharging fluid from said dispensing chamber; control means operable in a discharge mode to effect closing of said first normally open valve and opening of said second normally closed valve; and pressure means responsive to^' said control means in said discharge mode to supply pressurised fluid to said dispensing chamber thereby to discharge the contents thereof through said second valve.

Preferably, the pressurised fluid supplied to the dispensing chamber effects the closing of the first normally open valve and the opening of the second normally closed valve.

It is further desirable that the reservoir and dispensing chamber are normally maintained at negative pressure relative to the surrounding atmosphere and the second valve is maintained in the normally closed position by the negative pressure differential.

In a preferred embodiment, gas extracted from the reservoir to maintain the negative pressure therein is recirculated to subsequently pressurise the dispensing chamber in the discharge mode. Alternatively, however, a separate compressor may be used for this purpose and it should be appreciated that recirculation is not essential.

It is also desirable that the reservoir includes fluid detection means for detecting an inflow of fluid to the reservoir and more preferably means capable of distinguishing between an inflow of liquid and an inflow of gas.

Preferably, the control means are selectively operable in response to an output from the fluid detection means to initiate the discharge mode after a predetermined time interval, during which the dispensing chamber may be filled. Preferably, when an inflow of gas only is detected, the control means will not commence the discharge mode.

BRIEF DESCRIPTION OF THE DRAWINGS

A preferred embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawing wherein Figure 1 is a schematic diagram of a storage and metering device according to the invention.

PREFERRED EMBODIMENT OF THE INVENTION

Referring to the drawing, the fluid storage and metering device 1 comprises a reservoir 2 adapted to continuously receive fluids through an inlet 3. A dispensing chamber 4 is disposed below a reservoir outlet 5. A first normally open non-return valve 6 is disposed intermediate the reservoir and dispensing chambe .

A second normally closed non-return valve 8 is provided at an outlet 9 of the dispensing chamber 4 to which a discharge nozzle 10 is attached. Also connected with the reservoir 2 and dispensing chamber 4 are control means in the form of a central sequence controller, shown generally at 11.

The controller incorporates two vacuum switches 12 and 13, respectively linked to the reservoir by means of a first conduit 15. The controller operates pressure means 16 in the form, for example, of a vacuum pump or compressor 17 driven by a motor 18, as described in more detail below.

The input to the vacuum generator 16 is' connected with the reservoir 2 by a second conduit 20 incorporating a first solenoid valve 21. A third conduit 22 connects the high pressure output with the dispensing chamber 4. A second three way solenoid valve 24 is provided in the conduit 22 at a junction with conduit 20. A fourth conduit 23 connects conduit 20 with valve 24.

In use, gas entering the reservoir 2 via inlet 3 with a batch of fluid, causes the first vacuum switch 12 to provide a start signal to the sequence controller 11. The controller responds by initiating a delay sequence which continues for a pre-set separation time interval. During this separation interval, the controller 11 opens the first solenoid valve 21 thereby linking the vacuum generating source with the reservoir 2 via conduit 20 to maintain a negative pressure in the reservoir and dispensing chamber. The incoming liquid or slurry simultaneously drains under gravity into the dispensing chamber 4 through the first normally open non-return valve 6. The second valve is held closed by the negative pressure maintained in the dispensing chamber 4. Drainage of the fluid into the dispensing chamber is allowed to continue until the pre-set separation interval has expired, whereupon the controller commences the discharge cycle.

During the pressure or discharge cycle, the controller opens the second solenoid valve 24, thereby directing compressed air from the compressor 17 into the dispensing chamber 4 via conduit 22. The resultant pressure increase closes the first normally open non-return valve 6 thereby isolating the dispensing chamber from the reservoir. At the same time, the positive pressure in the dispensing chamber opens the second normally closed non-return valve 8, such that the waste is expelled under pressure through the discharge nozzle 10.

After a pre-set discharge time, the controller 11 closes the second solenoid valve 24, thereby re-setting the non-return valves 6 and 8 ready for the next input batch of waste fluid to the reservoir, whereupon the sequence repeats.

The second vacuum switch 13 is configured to detect entry of gas into the reservoir without liquid or solids. In such an event the switch signals the controller to open the first solenoid valve 21 to maintain the operating vacuum conditions within the reservoir and dispensing chamber, without activating the discharge cycle. As an alternative to the vacuum switches 12 and 13, a single watch responsive at two distinct levels may be used, for example.

In addition, the controller 11 may be fitted with a mechanism for over-riding the discharge function, for temporary storage of fluid within the reservoir 2. A counter, float switch, probe, pressure sensor or other level monitoring device may be provided to prevent overfilling in the storage mode.

It will be appreciated that by varying parameters such as the time intervals, the discharge chamber volume, the discharge conduit and the discharge pressure, the device can be adapted to produce discharges over considerable distances and heads in small batches. This facilitates controlled dispensing of the fluid whilst maintaining the reservoir 2 at all times available for concurrent and continuous collection of waste through the inlet 3.

Although the invention has been described with reference to specific examples, it will be appreciated by those skilled in the art that the invention may be embodied in many other forms. For example, it will be appreciated that the device can operate at atmospheric pressure in the reservoir. Furthermore, whilst the first and second valves described are pressure actuated, in other embodiments the valves can be controlled by other means and could, for example, be solenoid valves.

Claims

CLAIMS 1. A fluid storage and metering device comprising: a reservoir adapted to continuously receive fluids; a dispensing chamber disposed to receive fluid from said reservoir; first normally open valve means connecting said reservoir to said dispensing chamber; second normally closed valve means for intermittently discharging fluid from said dispensing chamber; control means operable in a discharge mode to effect closing of said first normally open valve and opening of said second normally closed valve; and pressure means responsive to said control means in said discharge mode to supply pressurised fluid to said dispensing chamber thereby to discharge the contents thereof through said second valve.

2. A device according to claim 1, wherein the closing of the first valve and the opening of the second valve is effected by pressurised fluid supplied to the dispensing chamber.

3. A device according to claim 2, wherein said pressurised fluid is air.

4. A device according to any one of the preceding claims, wherein the reservoir and the dispensing chamber are normally maintained at negative pressure relative to the ambient pressure of the surrounding atmosphere.

5. A device according to claim 4, wherein said negative pressure is maintained by said pressure means.

6. A device according to claim 4 or claim 5, wherein said second valve is normally maintained in the closed position by the negative pressure in the dispensing chamber.

7. A device according to claim 5 or claim 6, wherein said pressure means comprises a compressor or vacuum pump disposed to extract gas from the reservoir or dispensing chamber thereby to establish and maintain said negative pressure.

8. A device according to claim 7, wherein said extracted gas is at least partially recirculated by the pressure means to the dispensing chamber in the discharge mode.

9. A device according to any one of the preceding claims further including detection means to detect an inflow of fluid into the reservoir.

10. A device according to claim 9, wherein said control means are operable in response to a signal from said detection means to initiate said discharge mode after a predetermined separation time interval has elapsed.

11. A device according to claim 10, wherein said separation time interval is sufficient to permit the dispensing chamber to be substantially filled before initiation of the discharge mode.

12. A device according to any one of claims 9 to 11, wherein said detection means is capable of distinguishing between an inflow of liquid and an inflow of gas.

13. A device according to claim 12, wherein said control means is adapted not to initiate the discharge mode unless a signal from said detection means indicates that an inflow of gas is accompanied by an inflow of liquid.

14. A device according to any one of claims 9 to 13, wherein said detection means includes at least one pressure sensitive switch.

15. A device according to claim 14, wherein said detection means includes a first vacuum switch to detect an inflow of gas to the reservoir and a second vacuum switch to detect an inflow of liquid to the reservoir.

16. A device according to any one of claims 12 to 14, wherein said detection means includes a switch responsive at a first pressure level to indicate an inflow of gas to the reservoir and at a second pressure level to indicate an inflow of gas and liquid to the reservoir.

17. A device according to any one of the preceding claims, wherein said control means permits selective adjustment of discharge time, time between discharge cycles, separation time or discharge pressure.

18. A device according to any one of the preceding claims, wherein the control means permits deactivation of the discharge mode in a storage mode for temporary containment of fluid within the reservoir.

19. A device according to claim 18, further including level monitoring means to monitor the level of fluid within the reservoir.

20. A device according to claim 19, wherein said level monitoring means is operable with said control means to initiate the discharge mode in response to liquid level in the reservoir exceeding a predetermined limit, thereby preventing over-filling of the reservoir.

21. A device according to any one of the preceding claims, wherein said first and second valves are actuable by solenoid means responsive to said control means.

22. A device according to any one of the preceding claims, wherein fluid from said reservoir is gravity fed to said dispensing chamber.

23. A fluid storage and metering device substantially as hereinbefore described with reference to the accompanying drawings.