Centrifugal pump for de-watering

Abstract

A method of de-watering during intermittent dry running periods with a self-priming centrifugal pump is presented. Centrifugal pumps, as opposed to diaphragm pumps, are advantageous because they are less expensive and can provide greater capacity. The shaft seals are sensitive, however, to frictional heating when water flow is interrupted. In some situations, this fractional heating may desiccate self-priming. The inventive concept provides a continuous stream of pressurized water moving through the pump to cool the seal and sustain priming capability without substantially impairing the ability of the pump to resume wet operation.

Claims

1. A method comprising: providing a self-priming centrifugal pump comprising: an inlet port; an impeller within a volute; an internal chamber in fluid communication with the volute to deliver water from an air-water mixture expelled by the impeller back to the volute during a recycling mode; and a discharge port to discharge air from the air-water mixture out of the self-priming centrifugal pump during the recycling mode; and injecting water into the self-priming centrifugal pump to maintain a reservoir of water within the volute sufficient to cool a shaft seal of the self-priming centrifugal pump and generate the air-water mixture at the impeller to provide suction at the inlet port, wherein injecting the water into the self-priming centrifugal pump comprises injecting the water into the self-priming pump through the discharge port at a fraction of a pumping capacity of the self-priming centrifugal pump.

2. The method of claim 1, wherein the water is under line pressure.

3. The method of claim 1, wherein injecting the water at the fraction of the pumping capacity comprises injecting the water at a rate of approximately 3-5 gallons per minute to the self-priming centrifugal pump which is capable of operating at a rate of approximately 100-150 gallons per minute in a suction mode.

4. A method comprising: providing a self-priming centrifugal pump comprising: an inlet port; an impeller within a volute; an internal chamber in liquid communication with the volute to deliver liquid from a gas-liquid mixture expelled by the impeller back to the impeller within the volute during a recycling mode; and a discharge port to discharge gas from the gas-liquid mixture out of the self-priming centrifugal pump during the recycling mode; and providing a coupling in fluid communication with the volute, the coupling sized sufficient to accommodate delivery of a pressurized liquid from a pressurized liquid source to the volute in a quantity sufficient to support generation of the gas-liquid mixture to provide suction at the inlet port, wherein the coupling is in fluid communication with the volute through one of: the discharge port of the self-priming centrifugal pump; the inlet port of the self-priming centrifugal pump; and a drain port of the self-priming centrifugal pump.

5. The method of claim 4, wherein the pressurized liquid is water under line pressure.

6. The method of claim 4, wherein the quantity sufficient to support generation of the gas-liquid mixture to provide suction at the inlet port is less than a pumping capacity of the self-priming centrifugal pump.

7. A system comprising: a self-priming centrifugal pump comprising: an impeller; a volute at least partially surrounding the impeller, wherein the volute is sized to be partially filled with a liquid and partially filled with a gas during a recycle mode, the liquid and gas forming a mixture in response to rotation of the impeller during the recycle mode; and an internal chamber disposed on a side of the volute opposite the impeller, the internal chamber having a geometry to direct liquid separated from the mixture toward the impeller during the recycle mode; and a coupler attached to the self-priming centrifugal pump, the coupler forming a liquid path to provide a pressurized liquid from a pressurized liquid source to the volute in a quantity sufficient to support generation of suction at an inlet port, wherein liquid from the inlet port flows to the volute during a suction mode, wherein the coupler is attached to the self-priming centrifugal pump one of: upstream of an inlet port of the self-priming centrifugal pump; at approximately a discharge port of the self-priming centrifugal pump, and in direct fluid communication with a discharge pathway of fluid from the self-priming centrifugal pump; and at approximately a drain port of the self-priming centrifugal pump.

8. The system of claim 7, wherein the geometry of the internal chamber is further to direct liquid away from the impeller during the suction mode.

9. The system of claim 7, wherein the coupler further comprises a backpressure regulator to substantially prevent flow through the coupler away from the self-priming centrifugal pump.

10. The system of claim 7, wherein the quantity to support the generation of suction at an inlet port is less than a pumping capacity of the self-priming centrifugal pump.

11. The system of claim 7, wherein the pressurized liquid is delivered to the self-priming centrifugal pump at approximately 3-10 gallons per minute and the self-priming centrifugal pump pumps at approximately 100-150 gallons per minute in the suction mode.

Description

DESCRIPTION OF THE DRAWINGS

(1) Various other objects, features and attendant advantages of the present invention will become fully appreciated as the same becomes better understood through the accompanying drawings, in which like reference characters designate the same or similar parts throughout the several views, and wherein:

(2) FIG. 1 is a perspective view of the invention, illustrating a centrifugal pump connected to a source of streaming water;

(3) FIG. 2 is a partial exploded view of the centrifugal pump of FIG. 1 in perspective;

(4) FIG. 3 is a diagram showing the internal chamber of a self-priming pump during recycling mode;

(5) FIG. 4 is a diagram showing the internal chamber of a self-priming pump during suction mode; and

(6) FIG. 5 is a process diagram following the steps of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

(7) FIGS. 1 and 2 show the major components of the invention. Self-priming centrifugal pump 1 is comprised of engine 4 connected to housing 6. Housing 6 contains impeller 5 which receives rotary power from engine 4 through shaft 8. Shaft 8 is maintained water-tight by seal 9. Impeller 5 receives liquid material at its center through inlet port 2 and expels it outwardly, centrifugally, creating thereby pressure, or head. The expelled material is thrown into a circular path in volute 7 and exits there from through discharge port 3.

(8) In the preferred embodiment, a means for continuously cooling the seal 20 is facilitated by coolant port 21 in inlet port 2. In a particularly preferred embodiment, said means is a pressurized source of liquid 22. The pressurized source of liquid 22 may be water under line pressure supplied by hose 23. Coolant port 21 and hose 23 are connected in a manner that is sealed and prevents the suction from being vented. Coupler 21 and hose 23 may alternatively be connected at the discharge end of the pump, as shown in phantom line in FIG. 1.

(9) The pressure in the pressurized source of liquid 22 must be such that only a fraction of the pump capacity is utilized in processing the flow of liquid there through during a dry cycle. In other words, it is required that suction remains available in inlet port 2 to resume pumping when the cycle returns to wet. In a particularly preferred embodiment, the fraction of pump capacity is defined by the pressure source delivering 3-10 gpm to a centrifugal pump operating at 100-150 gpm.

(10) As shown in FIG. 3, a self-priming pump 30 has an internal chamber 31 which maintains a reservoir of water 32. A non-self-priming pump will become air-bound when air 33 enters the suction line, as may occur when the pumpage pool is intermittently drained. With the reservoir of water 32, however, the pump can create an internal circulation to remove the air 33 by settlement of water as the heavier fluid. The air-water mixture has sufficient consistency to create a vacuum at the inlet port 2; and, thereby, the pump will re-prime itself when the pumpage pool returns. During dry cycling, however, the reservoir of water 32 may become heated sufficiently to degrade the seal 9. The means for cooling the seal 20 introduces a stream of fresh water to prevent such over-heating.

(11) In alternative embodiments, a coolant port 21 may be located at the discharge side of the pump, or a coolant port 21 may be located at the drain port 25, as shown in FIG. 1. The coolant ports 21 and 21 supply pressurized liquid 22 directly into the internal chamber 31. The internal chamber 31 operates at a higher pressure during suction operation. When the pressure in the internal chamber 31 exceeds that of the pressurized source of liquid 22, a backpressure regulator 24 located in the supply line will prevent unwanted back flow. During dry operation, however, the pressure balance favors a continuous flow of the pressurized liquid 22 into the chamber to cool the recycling reservoir of water 32 and to prevent thereby the degradation of seal 9. The continuous flow also replenishes evaporative losses caused by friction heating during dry cycling and acts, accordingly, to prevent loss of prime.

(12) Construction materials are readily available. Centrifugal pumps, such as that shown in FIG. 1 can be found at pump supply distributors. In the specific case of FIG. 1, the self-priming centrifugal pump 1 is a NorthStar 2-inch semi-trash pump. Inlet port 2 and coupler 21 can be easily fabricated with 2-inch PVC pumping materials. The one-quarter inch hose 23 is a ubiquitous hardware item. Water for the pressurized source of liquid 22 can be supplied from any utility having line pressure, such as well or tap water

(13) A method of de-watering an intermittently dry pool 10 is shown in the process diagram of FIG. 3. The method comprises the steps of providing a self-priming centrifugal pump 11, connecting the impeller to an engine through a shaft and seal 12, establishing fluid communication between the inlet port and pool 13, and introducing a pressurized liquid to the input at fractional pump capacity 14.

(14) While a particular form of the invention has been illustrated and described, it will be apparent that various modifications can be made without departing from the spirit and scope of the invention. For example, the invention could be practiced with the pump located at an elevation below that of a body of water, such as a pond, by means of siphoning. Accordingly, it is not intended that the invention be limited, except as by the appended claims.