 of a vortex tube cluster in a treatment vessel followed by one or more sections of packed coalescing elements in the liquid stream.
Figure 12 illustrates a treatment vessel similar to that of Figures 10 and 11 but shows the combination of a vortex tube cluster, packed coalescing elements and perforated plate baffles.
Figure 13 shows a treatment vessel that employs the combination of a vortex tube cluster with an electrostatic field coalescer employed to remove small highly dispersed or emulsified water droplets from oil.
liquid level control means (well known in the art and not shown) is used to control the rate of liquid discharge so as to maintain liquid leve120.
Figure 2 is a horizontal cross-sectional view taken through an upper portion of the vortex tube cluster of Figure 1 showing a manifold 22 that receives an inlet stream through inlet 14 of the vessel of Figure 1, and showing a plurality of vertically positioned vortex tubes 24. Each vortex tube has an inlet 26 in the vertical side wall thereof. Fluids under pressure flow through inlet 26 in each of the vortex tubes and enter the vortex tube tangentially-that is, as a tangent to the interior cylindrical side wall 28 of each of the vortex tubes. A wedge is positioned in manifold 22 to better distribute the inlet stream into the vortex tubes. Instead of using a wedge manifold 22 may be tapered in cross-sectional area or narrowed to equalize flow from the inlet stream into the individual vortex tubes 24.
Figure 3 is a cross-sectional view of a single vortex tube 24 that is representative of the other vortex tubes shown in the cluster. The upper end of each vortex tube is partially closed with a top plate 30 having a concentric dry gas outlet opening 32 therein. The bottom end 34 of each vortex tube 24 is open to permit the flow of liquid out of the lower bottom end. A horizontally positioned bottom diverter plate 36 is spaced from the bottom 34 of the vortex tube to allow a circumferential liquid outlet passageway 38. Bottom diverter plate 36 is typically supported to vortex tube 24 by spaced apart stand-offs that are not shown but can be in the form of short-length metal rods welded to the interior or exterior surface of the cylindrical wall of the vortex tube.
A vortex tube functions to separate immiscible liquid and gas components of a process stream by utilizing artificially created gravity-that is, centrifugal force. The process fluids enter the manifold 22 and flow through wet gas inlet 26 into the interior of the vortex tube tangentially so that the wet gas swirls at a rapid rate within the vortex tube as illustrated by the dotted lines in Figure 3. The swirling gas forces entrained liquids against each vortex tube internal cylindrical side wall 28 where the liquid accumulates and flows downwardly by gravity to ultimately flow out of the vortex tube through liquid outlet passageway 38. The gas component of the process stream has substantially less density than the entrained liquid component, therefore the gas component migrates towards the axial center of each vortex tube 24 and flows out through the upper concentric dry gas outlet 32. The swirling gas takes the form of a vortex in a pattern similar to that shown by the vortex boundary 48 as seen in Figure 3.
Figures 1, 2 and 3 are representative of the state of the art to which this disclosures of this invention apply. This invention provides improved ways for use of vortex tube separation, and particularly vortex tube clusters, to obtain more effective separation of an entrained immiscible liquid component from a wet gas stream.
Systems disclosed herein can operate with one or more vortex tubes. Each vortex tube is typically oriented vertically but can operate as long as it has a vertical downward tangent. The use of vortex tube clusters is preferred. A separator can include a single vortex tube, cluster of vortex tubes or a plurality of clusters of vortex tubes depending on the volume of process fluids being treated. The length of each vortex tube can vary. If long length vortex tubes are employed a vertically oriented vessel may be preferred.
The improvements of the invention are illustrated in Figures 4 though 16 as will now be described.
Figure 4 is an elevational cross-sectional view of a horizontal separator vessel l0A that has an inlet 14, a dry gas outlet 18 and a liquid outlet 16.
Positioned within the interior of vessel 10A is a vortex tube cluster generally indicated by the numeral 40 as illustrated and described with reference to Figures 1 and 2. A liquid leve120 is maintained within vessel 10A. While the vortex tube cluster 40 functions to extract a substantial percentage of any entrained liquids entering through inlet 14 nevertheless in the usual case the gas that emanates from the upper ends of the individual vortex tubes making up cluster 40 can have some residual entrained liquid component.
To further de-mist the gas before it exits through gas outlet 18 the separator of Figure 4 includes a vane-type mist eliminator 42. Such vane-type mist eliminators consist of closely spaced parallel vanes, bent or formed to create a torturous path for gas passing therethrough. The vanes are very closely spaced and are usually short from leading edge to trailing edge.
Vane-type mist eliminators have been used previously in industry for augmenting the separation of entrained liquids from a gas stream but have a common problem in that they can easily become flooded with liquid if too much entrained mist is carried into them by the gas stream. Flooding occurs when liquid bridges the gap between adjacent vanes over a significant portion of the vane flow area. If flooded, liquid-in-gas carryover can result. The concept as revealed in Figure 4 is an improved way of using a vane-type mist eliminator 42 in the treatment of wet gas. The use of a vortex tube cluster 40 in advance of vane-type mist eliminator 42 results in removal of a substantial portion of entrained liquid from the wet gas stream before the wet gas stream passes through the vane-type mist eliminator, thus substantially reducing the possibility of flooding of the mist eliminator. The conzbination of a vortex tube cluster separation system with a vane-type mist eliminator minimizes the need for a large gravitation separation section in vessel 10A. Thus, the combination of the vortex tube cluster 40 and vane-type mist eliminator 42 can result in a significantly reduced size of vessel 10A required to treat a given gas flow stream rate to thereby reduce the overall cost of a separator.
The vane-type mist eliminator preferably closes the full interior area of vessel 10 above liquid level 20 -- that is, the lower edge of vane-type mist eliminator 42 extends within liquid retained in the lower portion of the vessel to ensure that all of the gas passing out from vortex tube cluster 40 passes through mist eliminator before exiting the vessel through dry gas outlet 18.
If the liquid extracted from wet gas flowing through the vessel 10A is of two-phase--that is, if the liquid includes, as an example, both a water phase and a hydrocarbon phase (such as crude oil), the liquid outlet may be separated into two portions. As shown in Figure 4 a partition wall 44 divides the lower portion of vessel 10A into two parts. Any hydrocarbon or lighter component of the extracted liquid will float on the surface of a denser liquid phase above an interface 45 and can flow over the upper edge 46 of partition wall 44 into a lower liquid interior section 48 of vessel 10A that has a lower liquid leve150. The lighter density (oil) phase having liquid level 50 may be withdrawn through a second liquid outlet 52. If the liquid component of the wet gas stream is of a single phase or if no separation of liquid components is required, then partition wa1144 and second liquid outlet 52 may be eliminated.
In the operation of the system of Figure 4, it would be necessary to have a liquid level control to regulate the height of liquid level 50 in the section 48 of the vessel interior and such liquid height control is not shown since it is well known and commonly, practiced in the art of gas/liquid separation.
Figure 5 is an alternate embodiment of the system of Figure 4 that employs the combination of a vortex tube cluster and a vane-type mist eliminator. In the arrangement of Figure 5, vessel lOB is a vertically oriented elongated cylindrical vessel that has an inlet 14, a vortex tube cluster 40, a dry gas outlet 18 and a liquid outlet 16, all functioning as described with reference to Figure 4. In Figure 5 the vortex tube cluster 40 is illustrated as if it has four separate vortex tubes rather than six (as in Figure 4) but the function is the same. As previously noted, the number of vortex tubes in a cluster can vary from one to many depending upon the volume of process fluids handled by the system and the physical arrangement of the vessel.
In the arrangement of Figure 5 a first lower partial horizontal shelf 54 and a second upper partial horizontal shelf 56 are utilized. Extending between shelves 54 and 56 is a vane-type mist eliminator 42 that is constructed like, and has the same function as, the mist eliminator in Figure 4. The dry gas passing out the upper ends of the individual vortex tubes making up vortex cluster 40 must pass through mist eliminator 42 before exiting the vessel through dry gas outlet 18. In this way, vane-type mist eliminator 42 will extract a substantial portion of any remaining liquid carried by the gas stream. Thus the arrangement of both Figures 4 and 5 places in series a vortex tube cluster 40 and a vane-type mist eliminator 42 to enhance the separation of interdispersed phases in the process stream.
Additional liquid extracted from the gas stream flowing through mist eliminator 42 in Figure 5 falls onto first horizontal shelf 54. An opening in the shelf receives the upper end of a conduit 58 by which liquid extracted by mist eliminator 42 is passed downwardly into the lower interior end portion of vessel l OB, the lower end of conduit 58 extending below liquid level 20.
separating entrained liquids from a gas stream and are formed by