Gas separation: apparatus – Degasifying means for liquid – Including means to remove mist entrained in gas
Reexamination Certificate
2003-04-24
2004-08-10
Hopkins, Robert A. (Department: 1724)
Gas separation: apparatus
Degasifying means for liquid
Including means to remove mist entrained in gas
C055S414000, C055S421000, C055S424000, C055S459100, C055S466000
Reexamination Certificate
active
06773492
ABSTRACT:
REFERENCE TO MICROFICHE APPENDIX
This application is not referenced in any Microfiche Appendix.
BACKGROUND OF THE INVENTION
This disclosure is to an improved vortex tube for use in separating an immiscible liquid component from a gas stream and more particularly for a system and a method of operating a system for separating liquid components from a gas stream. An example of an application of the invention is for separating entrained water from a natural gas stream.
The subject of the invention generally relates to gas/liquid separators or gas/liquid/solid separators. Separators of this type are typically process vessels that may be at atmospheric or above atmospheric pressures. The main function of the separator system is to segregate immiscible phases of the process stream such as when the process stream is the form of a gas, such as natural gas that carries with it an immiscible liquid component. The function of the separator of this invention is to separate out the liquid component to provide at the output of the separator a gas stream that is relatively free from entrained liquids.
Separators for separating liquid components from a gas stream are commonly utilized in the oil and gas industry, specifically in oil and gas production, oil refining and gas processing. While very commonly utilized in the oil and gas industry, separators of this type are also used in the mining industry, chemical plants, water treatment facilities, pulp and paper plants and pharmaceutical manufacturing facilities. Separators can be designed to separate a two-phase stream—that is, a vapor/liquid stream or a three-phase stream—that is, a vapor/organic liquid/aqueous stream or a four-phase stream—that is, a vapor/organic liquid/aqueous liquid/solids stream.
Separation of immiscible components of the stream usually and ultimately depend on the force of gravity. Gravity can be either natural gravity—that is, the pull of objects towards the center of the earth or created gravitational forces such as represented by centrifugal separators. Natural gravity is usually used by flowing a stream having immiscible components into a vessel which provides a quiescent zone—that is, a relatively undisturbed environment that allows gravity to act on heavier components of the stream and move them into a downward part of the vessel. This movement has the counteraction of the lighter components of the stream migrating to an upward part of the vessel. In this way, the heavier components—that is, liquids, can be withdrawn from the lower part of the vessel and the lighter components—that is, gases, withdrawn from an upper part of the vessel.
Another type of gravitational separator utilizes artificial gravity attained by centrifugal force. One way of generating artificial gravity is by the use of a vortex tube. A vortex tube is typically an elongated tube having a cylindrical interior wall that is preferably vertically mounted or at least mounted with a vertically downward tangent. Adjacent an upper end of the vessel is an inlet opening into the vortex tube, the inlet being arranged so that fluids flowing therein tangentially intersect the interior wall of the vortex tube and flow around the interior wall thereby creating centrifugal force that is applied to the components, the centrifugal force serving to move the heavier component—that is, the liquid component, towards the wall of the vortex tube while the lighter component is forced towards the interior of the vortex tube. In a typical vortex tube the gas is withdrawn from an upper central vortex opening while the liquid component is withdrawn from a liquid outlet in the bottom portion of the vortex tube. The invention herein pertains to improvements to vortex tubes and to methods of using the improved vortex tubes for separation of immiscible components of a gas stream.
For background information relating to the general subject matter of this invention reference may be had to the following previously issued United States patents:
PATENT NO.
INVENTOR
TITLE
1,836,004
Becker
Apparatus for Treating Gas
2,808,897
Reinsch et al
Apparatus for Contacting
Liquid and Vaporous
Materials
3,296,774
Hoogendorn et al
Gas-Liquid Contactor with
Wall Obstructions and
Contacting Method
3,498,028
Trouw
Apparatus for Contacting
Liquids and Gases
3,581,467
Donnelly
Method and Apparatus for
Vortical Liquid-Gas
Movement
3,605,388
Zuiderweg et al
Apparatus for Contacting
Liquids and Gases
3,662,521
Behar et al
Device for Reaction Between
Liquid Phase and Gaseous
Phase
3,930,816
Miczek
Structure for a Gas and
Liquid Contacting Chamber
in a Gas Effluent Processing
System
4,128,406
Spevack
Contact Apparatus for
Multiphase Processing
4,486,203
Rooker
Inlet Momentum Absorber
for Fluid Separation
4,838,906
Kiselev
Contact-and-Separating
Element
4,880,451
Konijn
Gas/Liquid Contacting
Apparatus
5,145,612
Reay et al
Apparatus for Mixing Vapor
in a Countercurrent Column
5,683,629
Konijn
Horizontal Tray and Column
for Contacting Gas and
Liquid
5,714,068
Brown
Inlet Device for Large Oil
Field Separator
BRIEF SUMMARY OF THE INVENTION
Separators are process vessels, commonly pressurized, which segregate immiscible phases of a process stream. They are commonly used in oil and gas production, oil refining, gas processing, mining, chemical plants, waste water treatment, pulp and paper, and pharmaceutical plants. They separate two-phase streams (vapor/liquid), three-phase streams (vapor/organic liquid/aqueous liquid) or four-phase streams (vapor/organic liquid/aqueous liquid/solids). Separators commonly have an inlet momentum absorber or deflector intended to utilize or reduce fluid incoming momentum, and distribute liquid and gas. This energy reduction initiates phase separation inside the separator vessel. These inlet devices are then followed by various types of de-misting, de-foaming, and/or liquid coalescing apparatus.
The most common separator inlet device is a “splash plate”—that is, a flat, curved or dished impingement plate that intercepts the incoming flow stream. Fluids are allowed to rebound in a direction considered least destructive to the quiescence of the bulk phases residing in the vessel. Splash plates are characterized by relatively high rebound turbulence. A diffusion inlet is another generic type of inlet device. It typically divides the flow stream into multiple smaller streams and reduces momentum by gradual enlargement of the flow areas of each stream.
The invention herein relates to a “vortex tube” that is frequently utilized in a “vortex tube cluster”. A vortex tube can be used as a momentum dissipating inlet device and can eliminate other phase separation elements as well. A vortex tube has an inlet through which fluids enter tangentially creating rotational flow. Centrifugal force separates phases within the tube, which then exit, gas from the top through a central gas orifice and liquids from the bottom through peripheral openings. A vortex is formed inside the tube. In a preferred embodiment, the bottom of each tube is submerged below the liquid surface to a depth that prevents the gas vortex from blowing out the bottom.
An essential characteristic of a vortex tube is that it uses flow energy constructively to separate phases whereas in impingement and diffusion devices flow energy is counterproductive to separation, and so they seek to dissipate flow energy as non-destructively as is practical. (“Destructive” refers to the tendency of hydraulic agitation to mix, rather than to separate phases). This invention herein includes an improved vortex tube that is usually employed in a vortex tube cluster.
The disclosure herein covers a vortex tube system which produces optimum performance for a variety of process circumstances and conditions.
One improvement described herein minimizes fluid shear by shielding the axially flowing gas stream leaving the top of the tube from the feed stream as it enters the tube tangentially. It consists of a ‘vortex finder’, which shields the vortex tube outlet stream from disturbance by the inlet stream. It is comprised of a vertical tube the same size
Gable & Gotwals
Hopkins Robert A.
Johnson Paul H.
National Tank Company
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