Froth handling pump

Abstract

A froth handling pump is provided which includes a pump casing, an impeller mounted within the casing, and a de-aeration chamber mounted to the rear side of the pump casing. The impeller comprises multiple pumping vanes, each of the vanes having an inlet angle and an outlet angle, wherein the outlet angle is greater than the inlet angle, the outlet angles terminating at a rear shroud. The rear shroud includes multiple vent holes for the passage of gasses therethrough. The de-aeration chamber, which comprises an inner volume, includes an inlet formed on the inner side for receiving gasses passing through the plurality of vent holes. At least one vent outlet is provided for the discharge of gasses from the de-aeration chamber.

Description

FIELD OF THE INVENTION[0001]The present invention relates to the field of centrifugal slurry pumps, and particularly, to froth pumps for handling bitumen froth.BACKGROUND OF THE INVENTION[0002]Centrifugal pumps, as the name implies, employ centrifugal force to lift liquids from a lower to a higher level or to produce a pressure. This type of pump, in its simplest form, comprises an impeller consisting of a connecting hub with a number of vanes and shrouds, rotating in a volute collector or casing. Liquid drawn into the center, or eye, of the impeller is picked up by the vanes and accelerated to a high velocity by rotation of the impeller. It is then discharged by centrifugal force into the casing and out the discharge branch of the casing. When liquid is forced away from the center of the impeller, a vacuum is created and more liquid flows into the center of the impeller. Consequently there is a flow through the pump. There are many forms of centrifugal pumps, including the type use...

AI Technical Summary

Benefits of technology

[0005]The present invention is directed to a froth handling pump, which significantly minimizes or eliminates the problems described herein during bitumen froth pumping. As used herein, “bitumen” refers to any of various flammable mixtures of hydrocarbons and other substances, occurring naturally or obtained by distillation from coal or petroleum.

Problems solved by technology

While bitumen froth is widely pumped and much is known about the process, a number of problems exist with froth pumps themselves and the pumping process.

First, bitumen froth pumps often “air lock.” This occurs when gasses accumulate in the suction of the pump under the action of the centrifugal forces operating on the fluid in the passages of a rotating impeller to form a bubble which partially blocks the suction and significantly degrades pump performance (as much as 40% to 70% loss in both flow and head).

With viscous flows like bitumen, this air lock can be particularly difficult to remedy due to the laminar, or near laminar, nature of the high viscosity flow.

Second, bitumen froth pumps cannot typically produce more than about 30 to 40 m of head, which is limited by the high viscosity of the bitumen and by the maximum speed at which the pump can be run before net positive suction head available (NPSHA) available to the pump suction falls below the minimum required to prevent cavitation in the pump impeller.

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