Abstract:
An apparatus for the efficient dissolution of fluids, both gas to liquid and liquid to liquid. A flow splitter divides the influent to an upper and lower stream. The lower stream is injected with a gas and the gas-enriched lower stream is subsequently discharged proximate to the bottom of a contactor in tangential fashion. The upper stream is discharged in similar tangential fashion proximate to the top of the contactor producing a vortex flow pattern. The countercurrent flow of the gas-enriched lower stream and upper stream ensures a high degree of dissolution of the gas in the liquid. Alternatively, two liquids of differing densities may be dissolved together with the present invention.

Description:
BACKGROUND OF INVENTION 
     1. Field of the Invention 
     This invention relates, generally, to the dissolution of a fluids and more particularly to fluid contacting systems. 
     2. Description of the Prior Art 
     There are many types of fluid contacting systems. A contact tank, or chamber, is commonly used to transfer a gas bubble to the bulk of the process water in a contacting system. Efficient mixing of the gas and the process water within the contacting system is critical in maximizing the performance of the system. More specifically, when a gas has a low solubility in water, the effective transfer of the gas to the liquid is critical. 
     Several types of fluid contactors have been developed with the most common including contactors that use diffused bubbles, positive pressure injection, negative pressure, a turbine mixer tank, and a packed tower. Diffused bubble contactors can have either a concurrent or countercurrent configuration. Countercurrent bubble contactors are the most efficient and cost effective of the alternatives and have been employed in the design of most gas dissolution systems. Positive pressure injection is most often employed with a U-tube where an eductor or Venturi tube provides negative pressure means to inject gas into the liquid flow. 
     Continuing efforts are being made to improve gas-liquid contacting tanks. By way of example, U.S. Pat. No. 5,968,352 to Ditzler that describes a contact chamber with concentric inner and outer tanks. Water is injected with gas prior to the water entering the concentric tanks. The gas-enriched water enters the tank configuration via a conduit and is discharged near the bottom of the inner tank so that it flows upwards to the top of the inner tank. As the water nears the top of the inner tank, the water overflows to the concentric outer tank where the water then flows downwards to the bottom of the outer tank and out. 
     U.S. Pat. No. 6,207,064 to Gargas describes a cylindrical contact tank that discharges gas-containing water near the upper end of the tank in a tangential orientation. The tangential discharge causes a turbulent swirling motion of the water within the tank to promote further gas contact with the water. 
     Similarly, U.S. Pat. No. 6,054,046 to Nelson describes a contact tank having a vortex chamber that creates a downward spiral flow of the gas-containing liquid stream. 
     The prior art does not utilize a concurrent flow of gas and liquid for facilitating the dissolution of gas in a liquid without the use of positive pressure or diffusers. 
     A fluid contacting system that improves the transfer of fluid contact which is simple in design and economical to maintain and operate is needed. 
     However, in view of the prior art considered as a whole at the time the present invention was made, it was not obvious to those of ordinary skill in the pertinent art how the identified needs could be fulfilled. 
     SUMMARY OF INVENTION 
     The long-standing but heretofore unfulfilled need for a contacting apparatus that increases the fluid contact that is simple in design and economical to maintain and operate is now provided in the form of a new, useful and non-obvious device. 
     The contacting apparatus includes a contactor and a liquid source that is in fluid communication with a flow splitter. The flow splitter is in further interposing fluid communication with a flow adjustment means and a gas injection means. The flow splitter splits the liquid influent into upper and lower streams. The upper stream is directed to the flow adjustment means and the lower stream is directed to the gas injection means. The flow adjustment means is in fluid communication with the splitter and an upper fluid flow directing means. The flow adjustment means is adjusted so that the upper stream flows at a desired flow rate. The upper stream is discharged tangentially at the desired flow rate via the upper fluid flow directing means. The upper fluid flow directing means is disposed proximate to the top of the contactor and at a preselected downward angle so that the upper stream discharge direction and velocity produces a downward vortex flow within the contactor. The gas injection means is in fluid communication with a gas source and is interposed between the flow splitter and a lower fluid flow directing means. The gas from the gas source is injected concurrently with the lower stream via the gas injection means to produce a gas-enriched lower stream. The lower fluid flow directing means is disposed proximate to the bottom of the contactor and at a preselected upward angle so that the gas-enriched lower stream discharge direction and velocity produces an upward vortex flow that is counter to the downward vortex flow within the contactor. A mixing zone is created by the upward and downward vortices because the gas-enriched lower stream flows in an upwardly direction and the upper stream flows downwardly to an outlet thereby producing a mixing countercurrent flow within the contactor. The outlet is disposed proximate to the bottom of the contactor. A gas collector disposed proximate to the top of the contactor collects gas not transferred to the liquid and recirculates the collected gas to an outlet conduit. 
     In an alternative embodiment of the invention, a fluid having a density lighter that the liquid may be substituted for the gas. Thus, a first liquid and a second liquid may be dissolved using the present invention provided they exhibit distinct densities. Accordingly, the second liquid rises in counter-vortex relation to the denser first liquid flowing downward. 
     It should be noted that virtually any gas including, but not limited to, ozone, ammonia, oxygen, carbon dioxide, nitrogen and the like may be dissolved using this novel invention. Additionally, the present invention may be used to dissolve together two fluids, each in a liquid state. 
     Potential applications for the present invention include, but are not limited to, laundry cleaning, swimming pool applications, produce washing, fish farm maintenance, hog farm effluent processing, toxic waste decontamination, industrial chemical processing, and the like. 
     An important object of the present invention is to provide an improved contacting apparatus that increases the efficiency of the transfer of gas to a liquid and thereby reduces operating costs. 
     Another object of the present invention is to provide a contacting apparatus that reduces maintenance requirements. 
     These and other important objects, advantages, and features of the invention will become clear as this description proceeds. 
     It is to be understood that both the foregoing general description and the following detailed description are explanatory and are not restrictive of the invention as claimed. The accompanying drawings, which are incorporated in and constitute part of the specification, illustrate embodiments of the present invention and together with the general description, serve to explain principles of the present invention. 
     The invention accordingly comprises the features of construction, combination of elements, and arrangement of parts that will be exemplified in the description set forth hereinafter and the scope of the invention will be indicated in the claims. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS 
     For a fuller understanding of the nature and objects of the invention, reference should be made to the following detailed description, taken in connection with the accompanying drawings, in which: 
     FIG. 1 is a front view of the present invention; 
     FIG. 2 is a partial top view of the present invention showing the direction of flow within the contactor; 
     FIG. 3 is partial bottom view of the present invention showing the direction of flow within the contactor; 
     FIG. 4 is a front view of a second embodiment of the present invention; 
     FIG. 5 is an isometric view of the invention; and 
     FIG. 6 is a partially sectional isometric view of the invention. 
    
    
     DETAILED DESCRIPTION 
     Referring now to FIG. 1, it will there be seen that the reference numeral  10  denotes an illustrative embodiment of the contacting apparatus as a whole. Contactor  20  is a longitudinally extending elongate hollow enclosure having a closed top  12 , a closed bottom  14 , and a gas tight interior space therein. Any suitably sized commercially available contactor may be utilized in the apparatus of the present invention. For example, Model #1016963, manufactured by Harvel. Similarly, any conventional flange and flange gaskets may be employed, for example Model C80272 and C80700 manufactured by Colonial. 
     As shown in FIG. 1, supply pump  50  pumps liquid from a remote source to flow splitter  30  via inlet conduit  52 . Any commercially available, suitable liquid pump may be utilized in the present application, for example Model #DB 1-½ manufactured by Jacuzzi. Preferably, flow splitter  30  is a conventional T-fitting. Alternatively, any means known in the art to split the flow of a liquid may be utilized as a flow splitter including but not limited to a Y-fitting. 
     Flow splitter  30  splits the flow into two streams so that an upper stream flows to influent conduit  16  and a lower stream flows to influent conduit  18 . The upper stream flows to a valve or flow adjustment means  32 . Preferably, this flow adjustment means  32  is a ball valve. Alternatively, any flow adjustment means known in the art may be utilized to control the flow rate. The flow rate of the upper stream is adjusted to a preselected flow rate by the liquid flow adjustment means  32 . As flow adjustment means  32  increases the flow rate of the upper stream, the lower stream flow is proportionally decreased. The desired flow rate of the upper stream ranges from at least 50 percent to not more than 80 percent, while the desired flow rate of the lower stream ranges from at least 20 percent to not more than 50 percent. In the preferred embodiment the desired flow rate of the upper stream is about 80% of the total flow and the remaining 20% flow is directed to the lower stream. The precise flow split between the upper and lower stream of the present invention is determined by the specific requirements of an application and adjusted accordingly. 
     Gas injection means  34  injects gas into the lower stream. In the preferred embodiment, the gas injection means is an eductor. The lower stream is designed to flow through a constricted area of eductor  34  at a flow rate that creates a negative pressure at a small orifice within eductor  34 . The increase in flow velocity of the stream through the eductor  34  results in reduced pressure. The negative pressure created by the increased velocity of the lower stream draws the gas into the lower stream flow. The gas is entrained in the lower stream and carried along as very fine bubbles. A gas generation means or source  40  provides gas to eductor  34  and because of the negative pressure within the eductor, gas is drawn into the lower stream flow from gas source  40  without the use of a pump or high pressure. Furthermore, using eductor  34  allows gas to not only be introduced into eductor  34  without a pump, eductor  34  allows gas to be introduced into the lower stream without a pump. Eliminating the requirement for a pump subsequently reduces associated energy costs and maintenance costs. The eductor is a low maintenance, reliable mechanism that can be used efficiently in the gas-liquid contacting process. Contacting systems that use diffusers must use a pump to increase the gas pressure to overcome the liquid pressure at the bottom of a contactor so that the gas can be introduced within the contactor. The liquid pressure within the contactor can be relatively substantial in a contactor that has more than a few feet of liquid depth. Prior art diffusers also require a high level of maintenance and are subject to clogging. 
     The lower stream flow rate is sufficient to create negative pressure with the majority of the total flow volume of the apparatus being directed to the upper stream in the preferred embodiment. After the lower stream passes through eductor  34 , the lower stream is now entrained with a high concentration of gas. The gas-enriched lower stream is then introduced into the interior of contactor  20  using lower fluid flow directing means  65 . Preferably, lower fluid flow directing means is a nozzle  65 . Alternatively, any means known in the art to direct the flow of a fluid may be utilized as the lower fluid flow directing means including but not limited to nozzles or angled apertures defined within influent conduit  18 . Lower fluid flow directing means  65  introduces the lower stream tangentially to the inside wall of the contactor producing a vortex flow. 
     Additionally, fluid flow directing means  65  is angled upwardly to discharge the gas-enriched flow towards the top of contactor  20 . As the lower stream is discharged, gas that was not transferred to the lower stream within eductor  34  is released into contactor  20  as gas bubbles. The gas bubbles travel in the vortex flow path created by the liquid discharge. The gas bubbles travel circumferentially in the contactor while slowly floating upwardly along the vortex flow path. The length of travel for the gas bubble is greatly increased by the vortex flow path thereby increasing the gas-liquid contact time. This is a significant feature for gasses that are not highly soluble in liquids, such as ozone, that require a substantial length of gas-liquid contact time to be transferred to a target liquid. The vortex flow path reduces the incidence of stagnant liquid in the contactor. 
     In the preferred embodiment of the present invention, the majority of the total flow is introduced into the contactor via conduit  52  directed to the upper stream. The upper stream flows through flow adjustment means  32  and is discharged through upper fluid flow directing means  60 . Upper fluid flow directing means  60  introduces the upper stream tangentially to the inside wall of the contactor producing a vortex flow. Upper fluid flow directing means  65  is angled downwardly so that the discharge flow is directed to outlet  72  located proximate to the bottom of contactor  20 . The upper stream travels downwardly and encounters the rising vortex flow of the gas-enriched liquid lower stream that was discharged from lower fluid flow directing means  65 . Preferably, nozzle  60  is the upper fluid flow directing means. Alternatively, any means known in the art to direct the flow of a fluid may be utilized as the upper fluid flow directing means including but not limited to nozzles or angled apertures defined within influent conduit  16 . 
     The countercurrent flow between the upper and lower streams produces an advantageous mixing zone or interface that increases the gas-liquid contact time and thereby increases the dissolution of the gas into the liquid. 
     First end  72  of discharge conduit  74  is disposed proximate to the bottom of contactor  20  and liquid (hereinafter effluent) flows up outlet conduit  74  under pressure. Gas not transferred to the liquid is released from the liquid and collects at the top of the contactor. Gas collector  80  located proximate to the top of contactor  20  collects the gas and recirculates the gas to outlet conduit  85  of the effluent. This further increases the dissolution of gas into the effluent. 
     Referring now to FIG. 2, the upper fluid flow directing means  60  is coupled or formed integrally with the upper influent conduit  16 . More specifically, upper fluid flow directing means  60  is configured tangentially to the inside wall of contactor  20  about the horizontal plane. In the vertical plane, fluid directing means  16  is disposed at about a 45 degree downward angle, or not less than 25 degrees and not more than 50 degrees downward angle. Similarly, lower fluid flow directing means  65  as shown in FIG. 3 is configured tangentially to the inside wall of contactor  20  about the horizontal plane and at about a 45 degree upward angle in the vertical plant, or not less than 25 degrees and not more than 50 degrees upward angle. The angles of the fluid flow directing means  60 ,  65  are adjusted as needed to maximize the dissolution of gas within the liquid. In the preferred embodiment, the vortex flow produced by the lower flow directing means  65  and upper fluid flow directing means  60  cooperate with one another providing a vortex flowing in a single direction, either clockwise or counterclockwise. The upper and lower fluid flow directing means  60 ,  65  may be configured to produce opposing vortex flows so that a more turbulent mixing zone is created within contactor  20 . 
     In an alternative embodiment of the invention, among others, as shown in FIG. 4, a second contactor  1   10  is disposed in parallel relation to first contactor  20 . Supply pump  50  pumps liquid from a remote source to flow splitter  30  via inlet conduit  52 . Liquid flows through conduit  52 , wherein the flow is split into two influent conduits  16  and  18  and respective upper and lower streams. The upper stream is then divided so that a portion of upper stream flow is directed to first contactor  20  and second contactor  1   10 . Likewise, the lower stream is split so that a portion of the lower stream is directed to the first contactor  20  and second contactor  110 . The flow directed to the first and second contactors  20 ,  110  can be adjusted to meet the requirements for the apparatus. 
     Fluid flow directing means  65  and  115 , introduces the gas-enriched lower stream into the interior of parallel contactors  20  and  110 , respectively. Lower fluid flow directing means  65  and  115  produce a vortex flowably introducing the lower stream tangentially to the inside wall of the respective contactor. Additionally, fluid flow directing means  65  and  115  are angled upwardly to discharge the gas-enriched flow towards the top of contactors  20  and  110 , respectively. As the lower stream is discharged, gas that was entrained within the liquid within gas injection means  34  is released into contactors  20  and  110  as gas bubbles. First ends  72  and  122  of discharge conduits  74  and  112 , respectively, are disposed proximate to the bottom of contactors  20  and  110 , respectively. Liquid flows upwards under pressure to outlet conduit  85 . Gas collectors  80  and  125  are located proximate to the top of contactors  20  and  110 , respectively, and collect and recirculate the gas to outlet conduit  85  of the effluent. The use of a second contactor in parallel configuration can either decrease the liquid flow rate, which increases the contact time in the columns, or in the alternative the flow rate can be proportionally increased. Any number of additional contactors can be employed to even further improve the efficiency of gas-liquid contact and the dissolution of gas in a liquid. 
     It will be seen that the objects set forth above, and those made apparent from the foregoing description, are efficiently attained and since certain changes may be made in the above construction without departing from the scope of the invention, it is intended that all matters contained in the foregoing description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense. 
     It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described, and all statements of the scope of the invention that, as a matter of language, might be said to fall therebetween. 
     Now that the invention has been described,