Heat and water integration process for an oil sand operation with direct steam injection of warm thickener overlfow

Abstract

A heat and water integration process for an oil sands operation includes subjecting warm oil sands tailings to thickening to produce thickened tailings and warm water overflow; subjecting the warm water overflow to direct steam injection (DSI) to produce steam heated thickener water; providing the steam heated thickener water to a unit of the oil sand operation; and producing the warm oil sands tailings from the oil sands operation. The oil sand operation unit may be an oil sand ore preparation unit and / or a primary separation unit, for example. The heated thickener water can replace water taken from pond inventories. The DSI may use excess, low quality, wet, low pressure and / or blow-down steam. The process enables improved heat and water usage in oil sands processing.

Description

FIELD OF THE INVENTION[0001]The present invention generally relates to the field of oil sands processing and in particular relates to a heat and water integration process for reuse of hot thickener overflow water.BACKGROUND[0002]Oil sands processing requires hot water for a number of unit operations. In particular, oil sands ore preparation and primary separation cells require hot water.[0003]It is known to recuperate water from fresh river sources or from large ponds used to store water previously used and affected by the oil sands processing. The recycle pond water can be heated and used in oil sands extraction operations, for example.[0004]However, recycle process water contains a number of contaminants such as residual bitumen, suspended mineral solids and various salts. Due to the composition of recycle process water, heating in conventional indirect heating devices—such as shell and tube or plate heat exchangers—results in fouling of heat transfer surfaces. One known mitigatio...

AI Technical Summary

Benefits of technology

The present invention provides a process for integrating heat and water in an oil sands extraction and bitumen production operation. This process involves subjecting a warm oil sands tailings stream to thickening to produce a thickened tailings component and a warm water overflow component. The warm water overflow component is then used as a hot slurrying medium in the oil sand operation or as froth under-wash in the primary separation unit. The process also includes supplying ambient recycle water to the oil sand operation and using direct steam injection to heat the recycle water and the warm water overflow component. The invention provides a system for implementing this process. The technical effects of the invention include improved energy efficiency, reduced water usage, and reduced emissions.

Problems solved by technology

However, recycle process water contains a number of contaminants such as residual bitumen, suspended mineral solids and various salts.

Due to the composition of recycle process water, heating in conventional indirect heating devices—such as shell and tube or plate heat exchangers—results in fouling of heat transfer surfaces.

However, as thickeners are prone to upsets, the variable composition of thickener overflow leads to fouling of heat exchanger transfer areas.

Thickener water is viewed as having low quality heat making it unsuitable for many applications in oil sands processing.

However, it has been generally viewed that direct steam injection is not suitable for several heating applications since the steam / condensate are lost to the process fluid, thus requiring higher upstream make-up water and water treatment requirements to compensate for the lost steam / condensate.

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