Liquid purification or separation – Processes – Separating
Reexamination Certificate
1999-06-18
2001-12-25
Savage, Matthew O. (Department: 1723)
Liquid purification or separation
Processes
Separating
C210S315000, C210S317000, C210S484000, C210S489000, C210S497010, C210SDIG005
Reexamination Certificate
active
06332987
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a coalescer element and, more particularly, to a coalescer element with enhanced coalescence.
2. Discussion of the Related Art
Coalescers, sometimes in conjunction with separators, including inertial separators, settling devices, and separator cartridges, are generally utilized in industrial processes to separate several phases present in fluids, i.e., gases and/or liquids. In some instances such fluids constitute dispersions of two or more immiscible liquids such as oil and water. In other instances, such fluids constitute suspensions of liquid and/or solid particles in gas. In addition to separation, coalescers generally draw together or conglomerate smaller portions of one of the phases present in the fluid.
The spectrum of applications where coalescers have been used to remove minor amounts of a first phase, known as a discontinuous phase, from a second phase in which it is suspended, known as the continuous phase, covers a considerable range of situations. For example, coalescers may be utilized to remove water from compressed gas streams such as air, helium, hydrogen, nitrogen, carbon dioxide, and natural gas.
Coalescers may also be utilized to remove contaminants found in natural bodies of water such as oil spills. Additionally, coalescers may be utilized to separate small amounts of moisture, i.e., water, from petroleum based fuels, including gasoline, diesel and aviation fuels, such as kerosene.
In a coalescing process, for example, the coalescence of water from a petroleum based fuel, the fuel containing the water is passed through a coalescer comprising a coalescing medium. The fuel, which is the continuous phase fluid, passes through the medium and flows toward a first outlet. As the water, which is the discontinuous phase fluid, passes through the medium it tends to collect on the surface of the coalescing medium and form small droplets which are forced through the medium by the continuous phase fluid. The coalescing medium may be formed from or coated with a material which facilitates the formation of the droplets and the conglomeration of these small droplets into larger droplets. The larger water droplets are more easily removed via a second outlet and are less likely to be re-entrained into the fuel.
A limiting factor in the effectiveness or efficiency of the coalescing process in the re-entrainment of the droplets of the discontinuous phase fluid into the continuous phase fluid after they emerge from the coalescing medium. Re-entrainment may occur because of a number of reasons. One reason re-entrainment may occur is because the droplets of the discontinuous phase are too small and may be easily carried along by the potentially high flow rates of the continuous phase fluid to the continuous phase outlet. Accordingly, the smaller the droplets, the more likely the chance of re-entrainment. In addition, the smaller the droplets, the more likely the chance of the droplets penetrating a separator cartridge or any other type of separator, if a separator is utilized. Similarly, the larger the droplets, the less likely the chance of re-entrainment because they are less likely to be carried by the continuous phase fluid to the continuous phase fluid outlet and the less likely to penetrate into a separator.
Various mechanisms have been tried to increase the size of the droplets of the discontinuous phase fluid. For example, socks, foam, nettings, fuzzy woven or non-woven materials, or combinations thereof positioned over the coalescing medium have been utilized to increase the size of the droplets. However, in high surfactant conditions, the above-referenced materials or combination of materials which may be utilized, increase the size of the coalescing elements.
SUMMARY OF THE INVENTION
The coalescer element embodying the present invention overcomes many of the limitations of the prior art by preventing or substantially minimizing re-entrainment of the discontinuous phase fluid into the continuous phase fluid.
In accordance with one aspect, the present invention is directed to a coalescer element for separating a discontinuous phase from a continuous phase of a fluid. The coalescer element comprises a coalescer medium having a downstream surface and a porous wrap structure cooperatively associated with the coalescing medium and including pores and a multiplicity of holes. The pores allow the passage of the continuous phase but resist the passage of the discontinuous phase. The holes, which arc substantially larger than the pores, allow the passage of both the continuous and the discontinuous phase and are arranged to resist re-entrainment of droplets of the discontinuous phase into the continuous phase portion of the fluid.
In accordance with another aspect, the present invention is directed to a method of coalescing a discontinuous phase from a continuous phase of a fluid. The method comprises directing a fluid through a coalescing medium droplets of the discontinuous phase portion being formed in the coalescing medium and the continuous phase passing through the coalescing medium. The method further comprises directing the continuous phase through pores in a porous wrap structure and through a multiplicity of holes formed in the porous wrap structure which are substantially larger than the pores and directing the discontinuous phase through the multiplicity of holes to resist re-entrainment of the droplets of the discontinuous phase into the continuous phase portion of the fluid.
The coalescer element of the present invention may be utilized in a wide variety of coalescing applications and may comprise various configurations. However, for any given application and any given configuration, the coalescer element is designed to enhance the efficiency of the coalescing process by substantially preventing the re-entrainment of the discontinuous phase fluid into the continuous phase fluid. Re-entrainment is substantially prevented by facilitating the formation of discontinuous phase droplets of a substantially uniform size that are large enough not to become re-entrained by the flow of the continuous phase fluid even in the presence of high flow rates. The coalescer element of the present invention utilizes a wrap structure to form the larger droplets.
The coalescer element of the present invention is designed to increase the efficiency of the coalescing process without having to increase the size of the coalescing medium, thereby allowing for less expensive and smaller or more compact coalescing systems. In addition, the coalescer element of the present invention may be utilized in exiting systems with only minor modifications, if any. Accordingly, the coalescer element provides an inexpensive and simple mechanism for enhancing the efficiency of all coalescing processes regardless of whether the coalescing process involves dispersions of two or more immiscible liquids, such as petroleum based fuels and water, or aerosols.
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Clendenning Michael A.
Griffin Angela M.
Hibbard James R.
Whitney Scott A.
Williamson Kenneth M.
Leydig , Voit & Mayer, Ltd.
Pall Corporation
Savage Matthew O.
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