Separation media and methods especially useful for separating water-hydrocarbon emulsions having low interfacial tensions

Abstract

Separation media, separation modules and methods are provided for separating water from a water and hydrocarbon emulsion and include a fibrous nonwoven coalescence layer for receiving the water and hydrocarbon emulsion and coalescing the water present therein as a discontinuous phase to achieve coalesced water droplets having a size of 1 mm or greater, and a fibrous nonwoven drop retention layer downstream of the coalescence layer having a high BET surface area of at least 90 m2 / g or greater sufficient to retain the size of the coalesced water droplets to allow separation thereof from the hydrocarbon.

Description

FIELD[0001]The embodiments disclosed herein relate generally to separation media and methods for separating water-hydrocarbon emulsions. In especially preferred forms, the embodiments disclosed herein relate to separation of water from a water-hydrocarbon fuel (e.g., diesel fuel) emulsion.BACKGROUND[0002]The need to separate emulsions of water and hydrocarbons is ubiquitous; historically impacting a broad array of industries. The separation of water-hydrocarbon emulsions has conventionally involved systems that rely on single or multiple elements, novel flow patterns, stilling chambers, parallel metallic plates, oriented yarns, gas intrusion mechanisms, and electrostatic charge. The balance of separation systems employ an element that contains a fibrous, porous coalescing media through which the emulsion is passed and separated. Irrespective of the system design, all water-hydrocarbon separation systems target the collection of emulsified drops into close proximity to facilitate coa...

AI Technical Summary

Benefits of technology

The patent describes a separation media that can separate water from a water and hydrocarbon emulsion. The media has two layers: a coalescence layer that coalesces the water droplets in the emulsion to form larger droplets, and a drop retention layer that retains the coalesced water droplets while allowing the hydrocarbon to pass through. The drop retention layer has a high BET surface area of at least 90 m2 / g, which is necessary to retain the size of the coalesced water droplets. The separation media can be used in modules that separate water and dewatered hydrocarbon from the emulsion. The method involves passing the emulsion through the coalescence layer to coalesce the water droplets, and then passing them through the drop retention layer to separate them from the hydrocarbon. The hydrocarbon has a low interfacial tension, which makes it easier to separate.

Problems solved by technology

Droplets adsorbed onto the solid media surface travel along fiber surfaces, and in some cases, wet the fiber surface.

Conversely, a coalescence media is considered to be functionally unsuccessful for breaking an emulsion if the drops remain sufficiently small at the point of exit from the media that they remain entrained by the continuous phase and fail to separate.

In this regard, one root cause of prior art fibrous, porous coalescence media failure in sub-25 interfacial tension hydrocarbons is the presence of increased surfactancy.

In cases of sub-25 interfacial tension hydrocarbons, emulsion separation requires more complex systems that often involve nested pleated elements, flow path controllers, wraps, and stilling chambers.

This is the lowest energy conformation of the surfactant, and it results in depressed hydrocarbon-water interfacial tension.

Finally, surfactants associate with surfaces of media and water drops, and interfere with the unique surface interactions between media and water that destabilize water within the fuel and allow its separation.

As a result, the fuel pool available for non-gasoline transportation and power generation is rapidly transitioning to an interfacial tension region where prior art fuel-water emulsion separation media fail to remove water from the hydrocarbon.

Despite shifts in fuel interfacial tension, water remains a fuel contaminant of concern for corrosion of steel engine components and promotion of microbiological growth.

Further, engine emission compliance with the EPA 2007 Highway Rule depends heavily upon high pressure fuel injection equipment that is extremely sensitive to water.

These needs often preclude the complex separation systems that are conventionally known.

Media of the prior art often require multiple layers to affect the single function of separation of water-hydrocarbon emulsions, without guarantee of successful separation in high surfactant content, low interfacial tension hydrocarbons.

Incorporation of a coalescing media into a multi-layered, multi-functional coalescing media structure with a layer on the downstream side of the coalescing layer creates the possibility of media failure in high surfactant (i.e., sub-25 interfacial tension) hydrocarbons due to re-emulsification of the previously coalesced drops.

Images