Process and apparatus for in-line densification of a heterogeneous fluid using acoustic energy

Abstract

An inline process for imparting sonic energy plus a liquid gas separator to a continuous flow of a heterogeneous liquid to de-gassify the liquid and thereby provide for separation and extraction of selected liquid and gas components. The device utilizes a flat plate oriented in the direction of flow within the liquid so as to impart pressure fronts into the liquid to initiate liquid gas separation followed by a line pressure regulation, fluid jet stream, device to impart fluidic shear to fluid jet stream, and a separation vessel to facilitate mass transfer.

Claims

1. A method for degassing a fluid stream comprising: providing an incoming multiphase fluid stream having a first component with a first vapor pressure and a second component having a second vapor pressure higher than the first vapor pressure; generating bubbles in the multiphase fluid stream by applying acoustic energy to the multiphase fluid stream; increasing sizes of the bubbles in the multiphase fluid stream by reducing pressure of the multiphase fluid stream; directing the multiphase fluid stream having the bubbles of increased size onto a surface to burst the bubbles to separate gas in the bubbles from a liquid portion of the multiphase fluid stream, wherein the liquid portion has a low density liquid and a high density liquid; and passing the low density liquid through a first flow control device; passing the high density liquid through a second flow control device, wherein the surface is arranged in a substantially closed vessel.

2. The method of claim 1 further comprising: accelerating the multiphase fluid stream having the bubbles of increased size to form a jet.

3. The method of claim 1, further comprising: drawing the gas from the bubbles out of the substantially closed vessel.

4. The method of claim 1, further comprising: collecting the liquid portion at a bottom of the substantially closed vessel.

5. The method of claim 1, further comprising: heating the multiphase fluid stream.

6. The method of claim 1, wherein the acoustic energy applied to the multiphase fluid stream is applied by acoustic emulsion breaker.

7. The method of claim 1, wherein the surface causes a change in momentum of the multiphase fluid stream.

8. The method of claim 1, further comprising: capturing the gas.

9. The method of claim 1, further comprising: retaining liquid portion.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is an illustration of the process flow diagram.

(2) FIG. 2A is an illustration of the sequential process flow diagram of the preferred embodiment of the arrangement of the present invention.

(3) FIG. 2B is an illustration of an alternative sequential process flow diagram.

(4) FIG. 3 is an illustration of the process with multi-phase separation vessel.

(5) FIG. 4 is a graphic showing a comparison of a hydrocarbon composition post conventional heater treater stabilizer and the present invention of the preferred embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION

(6) The present invention comprises a preferred embodiment for the degassing of high API Gravity and high Reid Vapor Pressure hydrocarbon fluids. The process begins with the input of a heterogeneous fluid which a multi-phase fluid is containing constituent phases including gaseous phases dissolved in the liquid phase. The Liquid (1000) enters the process and is fluidly connected to the Acoustic Emulsion Breaker (AEB) (1010). The liquid under process enters an acoustic reaction chamber wherein the fluid under process is exposed to an acoustic signal of a nominal frequency of 1,000 Hz. The operating frequency is largely related to the preferred resonant mode of operation of the acoustic source. The degassing phenomenon is known to occur over a wide range of frequencies from 100 Hz.fwdarw.1M Hz depending upon the acoustic source geometry and architecture. The acoustic signal is preferably a square wave, where those skilled in the art will know that a square wave signal has higher order harmonics that enhance the degassing phenomenon.

(7) The AEB (1010) is fluidly connected to a Back Pressure Device [1020] (which may be positioned upstream or downstream of the AEB) that provides a means of supplying back pressure within the process upstream of the Back Pressure Device [1020]. A Back Pressure Device (2040) can be comprised of a single element or a plurality such as back pressure regulators [2020] and nozzles [2030] (see FIGS. 2A and 2B). Those skilled in the art will know that backpressure can be supplied by frictional drag in a fluid conduit, back pressure regulators, nozzles, orifice plates, venturi but is not limited to this list. Those skilled in the art will recognize that the preferred method of supplying back pressure is dependent upon the process operating conditions such as the following, but not limited to: fluid surface tension, flow rates, temperature, system downturn, and other factors.

(8) Alternatively, the sequential process steps of the present invention include the placement of a back pressure regulator [2020] upstream of the AEB [2010] (see FIG. 2B). This arrangement has utility in applications where pre-conditioning the liquid under process prior to acoustic stimulation by the AEB [2010] is desired.

(9) Fluidly connected to the Back Pressure Device (2020) is a Shear Device (2030) that imparts shear forces within the Liquid (2000) under process that promotes the disengagement of the gas phase with the Liquid (2000). The shear device 2030 and the back pressure regulator 2020 are operably fluidly connected but separated by a pressure vessel wall 2070.

(10) A Two (2) or Multi-Phase Separator (1030) is fluidly connected to the Shear Device (2030), wherein the Liquid (1000) under process proceeds to a second Multi-Phase Separator (1030) that is designed to retain the Liquid (1000) for completing the disengagement process between the Gas (1050) and the Liquid (1000). The Multi-Phase Separator (1040) may include devices such as Shear Plate (2060)(see FIG. 2A, 2B) or 3060 (see FIG. 3) upon which the Liquid (1000) under process is projected with which, a jet of the Liquid (1000) of sufficient velocity and angle of impact impart desired levels of shear stress promoting the evolution of Gas (1050) from the Liquid (1000) stream. Those skilled in the art will recognize that there are a number of fluidic devices such as nozzles, high shear nozzles, wire mesh packs, divergent vanes, and other components that can be utilized to impart desired shear forces into the Liquid (1000). The proper selection will be based upon physical properties of the liquid under process, optimized to process flow rates and operating conditions of the system. Further, the means of gas evolution from the liquid is not limited to the above mentioned apparatus.

(11) The secondary separation of the Liquid (3000) and Gas (3120) phases is conducted within a closed Vessel (3090), a Multi-Phase Separator (1030). The Multi-Phase Separator (1030) typically has orientation in the vertical or horizontal direction, but is not limited to such as depending upon the optimal system parameters and physical packaging. The Vessel (3090) will contain a Gas Space (3170) and a Liquid Space (3070 and 3080) in which secondary separation of Gas (3120) from the Liquid (3000) is achieved. A tertiary separation of the liquid emulsion of low density Hydrocarbon liquids (3070) and other higher density liquids such as Water (3080) are free to separate.

(12) Gas (3120) evolved from the Liquid (3000) under process is fluidly conducted to downstream processes such as compression, flare or other gas control measures. Control of Gas (3120) within the Vessel (3090) requires pressure regulation by means of a pressure regulator (3100) such that the discharge pressure is suited for the downstream processes. For applications where the evolved gas does not require sequestration and control, the separation Vessel [3090] may be vented to the atmosphere.

(13) The internal structure of the Vessel (3090) is not limited to any element or combination of elements including, but not limited to: baffles, surge suppressors, foam breakers, down comers, de-misting stages, trays, structured or random packing, etc.

(14) Liquid Level (3070 and 3080) within the Vessel (3090) is not limited in any manner. Frequently, the Liquid (3000) under process is an emulsion of hydrocarbon, Brine, Solids and Water (BS&W). The AEB (3010) is known to promote the destabilization of these emulsions, leaving a Low Density Liquid (3070) of hydrocarbon product and High Density Liquid (3080) of BS&W. Total liquid levels of both the Low Density Liquid (3070) and High Density Liquid (3080) and their discharge is maintained by Flow Control Devices (3140 and 3150 respectively). Flow Control Devices (3140 and 3150) may be comprised of any mechanism and is not limited to the following list: gravity, mechanical and/or electrical sensors, electrical and/or mechanical controllers and electrical and/or mechanical valves are utilized in the preferred embodiment of the present invention. Those skilled in the art will recognize that liquid level control design will be dependent on a variety of factors that make selected solution appropriate for a realized application.

(15) Effectiveness of gas 3120 evolution and final liquid composition (3070 and 3080) is based upon process parameters. Some process parameters that effect the final composition are the internal pressure of the Vessel (3090), temperature of the liquid under process, and acoustic power per unit volume of liquid processed. Increasing pressure within the Vessel (3090) tends to inhibit release of <C.sub.3 hydrocarbon species from the liquid. Increasing temperature increases overall vapor pressure of the fluid that enhances removal of C.sub.3-C.sub.5 hydrocarbon species. Further increasing the acoustic power per unit volume of liquid processed increases the thermal content of the evolved gas, while increasing the overall density of the fluid.

(16) The effectiveness of the process is shown in FIG. 4, showing the molar percentage change in the hydrocarbon composition of a Condensate processed with conventional thermal stabilizer, a heater treater as is known in the art (4000) is compared to that processed via the ACS (4010) of the present invention. Both the Heater Treater (4000) and ACS (4010) effectively removed 100% of the Nitrogen, Carbon Dioxide and Methane from the Liquid (3000) under process. However, the ACS (4010) was able to remove significantly greater percentages of the Ethane, Propane, Isobutane, n-Butane, 2,2 Dimethylpropane, Isopentane, n-Pentane, 2,2 Dimethylbutane, Cyclopentane and 2,3, Dimethylbutane than the Heater Treater (4000). The apparent negative percentage removal of the 2 Methylpentane plus components in the ACS (4010) graph is an artifact of the final molar percentage not normalized to the final volume of processed Liquid (3070).

(17) Having thus described the invention in connection with the preferred embodiment thereof, it will be evident to those skilled in the art the various revisions and modifications can be made to the invention described herein without departing from the spirit and scope of the invention. It is my intention, however, that all such revisions and modifications that are obvious to those skilled in the art will be included within the scope of the following.