Patent Grant
9956532
Technical Field
The embodiments herein generally relate to fluid hydraulic system design, and, more particularly, to combining at least two miscible fluids through a controlled uniform and axi-symmetric mixing of such fluids.
Description of the Related Art
In conventional fluid hydraulic system design, induction of a swirl into a main flow of a fluid typically use conventional tangential injection methods, which are characterized by utilizing numerous tangential injection ports (e.g., 1, 2, 3, 4 or more), stirred tank methods or swirl vane devices. For example, a conventional Quad-Port tangential injection device and a streamline plot of its swirl pattern is shown in
Moreover, conventional swirl generators require significant calibration, unique to each test configuration, of the entire apparatus to produce the desired swirl characteristics. For example, to modify the swirl flow intensities from a swirl vane, the entire swirl vane device requires replacement. Swirl vanes and other conventional swirl generators also introduce substantial pressure drops to fluid systems where the swirl is introduced.
What is desired is a uniform axi-symmetric swirling flow; for example, mixing and stirring for process flow engineering. Furthermore, is it desirable that such a swirling flow be predictable and does not introduce a substantial pressure drop to the system.
In view of the foregoing, an embodiment herein provides a swirl generator, comprising: a central chamber; an upstream nozzle connecting with an first end of the central chamber; a conical downstream nozzle connecting with a second end of the central chamber; and at least one injector having: a plenum having a plenum inlet and a plenum discharge; a slot connecting at a first end with the plenum discharge and connecting radially tangentially at a second end with the central chamber; and a plenum feed connecting with the plenum inlet. Such a system may further comprise: an inner spacer connected to an outer surface of the conical downstream nozzle; and an outer spacer connected to an inner surface of the conical downstream nozzle, wherein the inner and outer spacers forming a throat and defining a gap between a downstream edge cone surface and an inner surface of the downstream nozzle. Additionally, such a system may further comprise a thermally conductive jacket connecting with the central chamber.
In addition, embodiments herein include a method of generating an axially-symmetric swirling flow that comprises feeding a first flow into a plenum; discharging the first flow from the plenum into a converging gap; and radially tangentially discharging the first flow from the converging gap into a main flow. Such a method may further comprise feeding the first flow into the plenum in a direction perpendicular to the main flow. Additionally, the method may further comprise reducing a hydraulic diameter of the discharge gap. Moreover, the method may further comprise adding a first chemical reactant to the plenum. Furthermore, the method may further comprise adding a second chemical reactant to the main flow.
Additional embodiments disclosed herein provide a method of creating an axially-symmetric swirling flow, comprising: passing a main flow through a chamber having an upstream nozzle and a downstream nozzle; injecting a second flow into a plenum; passing the second flow from the plenum into a slot connecting at a first end with the plenum and connecting radially tangentially at a second end with the chamber; and mixing the second flow with the main flow. Such a method may further comprise injecting the second flow into the plenum in a direction perpendicular to the main flow. That method may further comprise reducing a hydraulic diameter of the downstream nozzle. Moreover, that method may further comprise adding a first chemical reactant to the plenum and may further comprise adding a second chemical reactant to the main flow. In addition, the method may further comprises discharging the first flow from the plenum into a converging gap and may further comprise reducing a hydraulic diameter of the discharge gap and may increase a velocity of the axially-symmetric swirling flow when a hydraulic diameter of the discharge gap is reduced or reducing the hydraulic diameter of the discharge gap may comprise: increasing an inner spacer connected to an outer surface of the downstream nozzle, wherein the inner spacer includes an inner spacer depth; and increasing an outer spacer connected to an inner surface of the downstream nozzle, wherein the outer spacer includes an outer spacer depth, in such a method, when reducing the hydraulic diameter of the discharge gap, the method may include computing a hydraulic diameter as a function of the inner spacer depth and outer spacer depth, and a Reynolds number.
Moreover, in the method, a rotation of the axially-symmetric swirling flow is either a clockwise swirl or a counterclockwise swirl. Such a method may further comprise switching the rotation of the axially-symmetric swirling flow by re-orienting the chamber.
These and other aspects of the embodiments herein will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. It should be understood, however, that the following descriptions, while indicating preferred embodiments and numerous specific details thereof, are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the embodiments herein without departing from the spirit thereof, and the embodiments herein include all such modifications.
The embodiments herein will be better understood from the following detailed description with reference to the drawings, in which:
The embodiments herein and the various features and advantageous details thereof are explained more fully with reference to the non-limiting embodiments that are illustrated in the accompanying drawings and detailed in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.
The embodiments herein create axi-symmetric uniform flow fields in a predictable and accurately quantifiable manner while significantly reducing the pressure drop associated with historical swirl-generating devices. In conventional swirl generators, such as those which rely on a device residing in the flow stream itself (such as chevron-like devices, swirl vanes, etc.), the conventional device itself is positioned inside the pressure boundary of the flow stream thereby creating “form loss” due to the leading edges of the conventional device that are impinged by the flow stream. These edges create a type of “bluff body” that resist flow, and in turn, produce an observable and definable pressure drop. In contrast, embodiments described herein only injects a fluid into a flow stream and does not induce a form loss. Additionally, embodiments herein anticipate pressure losses within the swirl flow generator itself; for example, between the injection piping and the converged swirling flows inside of the plenum. Beyond the swirl flow generator, however, very little pressure losses are anticipated in the main stream flowing through the swirl flow generator.
Referring now to the drawings, and more particularly to
As shown generally in
Generally, the mixing induced by the present subject matter can include but not be limited to the need to mix two miscible but not necessarily identical fluids, compositions, or reactants where controlled uniform axi-symmetric mixing is desired. In other words, swirl flow generator 1 induces a uniform and ax i-symmetric swirl, circumferentially around the discharge location (e.g., slot 40) and thereby imparting repeatable and controllable swirl. Thus, when installed, swirl flow generator 1 produces a known quantity of swirling flow from an incoming flow to produce a uniform axi-symmetric flow velocity profile at its discharge. To improve the swirl plenum performance for producing a known quantity of swirling flow, an incoming flow may be flattened using a flow straightener that produces a flattened velocity profile to swirl flow generator 1. In certain exemplary embodiments of the present subject matter, the device is configured as a continuous chemical reactor. Moreover, while main pipe 5 is illustrated as a circular pipe, other fluid channels of other shapes can be used instead of and/or in addition to the circular pipe shown as main pipe 5 without departing from the scope of the present subject matter.
Upstream nozzle 200 can be manufactured through a variety of different methods and the interface flanging can be modified to meet the needs of the application and installation requirements. As used herein, the interface flanging of upstream nozzle 200 refers to exterior surfaces used to attach the device to a piping system. Interface flanging can take many forms, depending to the requirements of the piping system. For example, mechanical attachment to the piping system can be realized by a flange or a weld. Flanges can be procured from off-the-shelf commercial sources or they can be custom made; in either case, the flange size will assure matching inside diameter surfaces. If welded, both inlet and discharge interior weldments are ground and machined smooth to that of both the device and the matching piping inside diameter surfaces, according to embodiments herein. Properly matched flanges or smoothed weldments assure predicable swirling discharged flow fields. In contrast, conventional systems that use mis-matched dimensions produce a diametric lip condition that introduces an undesirable hydraulic disruption to the desired uniform swirl flowfield. Additionally, upstream nozzle 200 contains features used to install, insert, and secure outer spacer 600 and inner spacer 650. For example, as shown in
Downstream nozzle 300 can be manufactured through a variety of different methods and the interface flanging can be modified to meet the needs of the application and installation requirements. Interface flanging can take many forms, depending to the requirements of the piping system. For example, mechanical attachment to the piping system can be realized by a flange or a weld. Flanges can be procured from off-the-shelf commercial sources or they can be custom made; in either case, the flange size will assure matching inside diameter surfaces. If welded, both inlet and discharge interior weldments are ground and machined smooth to that of both the device and the matching piping inside diameter surfaces, according to embodiments herein. Properly matched flanges or smoothed weldments assure predicable swirling discharged flow fields. In contrast, conventional systems that use mis-matched dimensions produce a diametric lip condition that introduces an undesirable hydraulic disruption to the desired uniform swirl flowfield.
Preferably, outer spacer 600 and inner spacer 650 are of equal depth and adjustments in their collective depth permit throat 60 of swirl flow generator 1 to be adjusted to wider or smaller hydraulic diameters. Alternatively, swirl flow generator 1 can be assembled without outer space 600 and inner spacer 650. In its “ring-less” assembled condition, throat 60 is at its widest, i.e., has its largest hydraulic diameter. Thus, as wider spacing pairs are included in the assembled swirl flow generator 1, the discharge throat narrows and thus the hydraulic diameter is reduced.
As described above, swirl flow generator 1 is an apparatus used to induce an axi-symmetric swirling flow to an incoming normalized and uniform flow to a conventional pipe (e.g., main pipe 5). In many applications, mixing and stirring with a uniform axi-symmetric swirling flow is a necessary attribute. Swirl flow generator 1 induces a uniform and axi-symmetric swirl, circumferentially around the discharge opening (e.g., slot 40), thus imparting repeatable and the controllable swirl and mixing condition of interest. Swirl flow generator 1 also performs the swirl injection at a low pressure drop in comparison to a more traditional swirl vane method. This is in contrast to prior art methods and devices that to do not provide uniform axi-symmetric swirling flow and are difficult to effectively meter and adjust.
The ability to precisely control the swirl injection flow rate out of plenum 20 is achieved by first knowing the tangential injection of flow rate into plenum 20. This flow in-turn creates a rotating motion inside and plenum 20 uniformly mixes the flow by turbine-like motion and circumferentially discharges the flow into incoming flow 30 through slot 40. Moreover, slot 40 is sized to meet desired swirl generation performance requirements. The ability to apply multiple ports adds mass flow to plenum 20 itself, but also permits those injections to contain reactants. With reactants added to plenum 20, the plenum itself becomes a continuously stirred tank reactor (CSTR) with its discharge containing the product of the reactants. These discharge products can in-turn react with reactants contained in incoming flow 30, once it is discharged through slot 40. In other words, according to one embodiment herein, the reaction process is segmented into two stages—one inside of plenum 20 and the other located at the slot discharge-to-main flow stirring region. The benefit of such embodiment is clear when reactants require special treatment (e.g., special kinetic or thermal treatment) or when the product's molecular and particulate size attributes are best defined by staged reaction methods. For example, plenum 20 could be constructed using special surfaces that catalytically promote the reaction or could be constructed to include a thermal jacket, where heat could be removed from the plenum region or could be added, depending upon the reaction requirements.
Swirl flow generator 1 can be installed in its assembled condition into any piping system (preferably using standard flanges), or it could also be welded into a piping system as a more permanent but less serviceable installation. The design permits either CW or CCW direction of swirling flows by simply re-orienting central chamber 110, as described above. Materials used to manufacture swirl flow generator 1 can be selected and properly sized to match to any piping system, including the use of polymer or ceramic materials. For example, according to one embodiment, swirl flow generator 1 is fabricated using stainless steel materials.
The intensities of the swirling flow of swirl flow generator 1 are attributable to the width of slot 40, gap 50 and throat 60. A significant benefit of the disclosed subject matter is knowing the intensity of the swirl and/or being able to reliably predict the swirl intensity metrics. In particular, the subject matter disclosed herein includes two basic swirl metrics: a Swirl Momentum Flux Ratio (SMFR) and a swirl number (SN). The SMFR is defined as the square of the ratio of momentum flux through the tangential inlets to that of the main inlet pipe:
where:
The swirl number (SN) is simply a ratio of velocities of a tangential jet (Vjet) to the inlet flow velocity (Vt)=Vjet/VT. Thus, for the dual port swirl generator, the SN jet uses either the upper or lower velocity (assuming they are equally split) in the numerator.
As described above, the flow area changes in swirl flow generator 1 as outer spacer 600 and inner spacer 650 widths change. Table 1, shown below, expresses this change in flow area (along with
In addition, computational fluid dynamics (CFD) analyses have been done on the disclosed subject matter with SMFR value between −0.069 to −0.8. The results are shown in
The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the appended claims.
This patent application claims priority to U.S. Provisional Patent Application No. 61/901,251, filed Nov. 7, 2013.
The United States Government has rights in this invention pursuant to U.S. Department of Energy Contract No. DE-NR0000031.
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