Gas transfer energy recovery and effervescence prevention apparatus and method

#The present invention relates to the field of gas transfer devices, and in particular to systems and methods for dissolving at least one gas into a liquid.

#There are many instances when it is desirable to dissolve a gas, whether soluble or insoluble, into a fluid that may already contain other dissolved gases. For example, the macro and microbial organisms in all rivers, lakes, oceans, and all aerobic wastewater treatment processes are based on the presence of sufficient dissolved oxygen to sustain their life processes. Normally, in undisturbed bodies of water there is a rather low density of macro and micro organisms in the surface water and the limited natural absorption of oxygen from the air into the water is sufficient to maintain sufficient concentrations of dissolved oxygen in the water to sustain the life processes of that body of water. However, with increased population density and industrial activity, the associated organic water pollution causes a high microbial oxygen demand that natural oxygen aeration processes cannot begin to provide sufficient oxygen resources. Thus, artificial aeration mechanisms are required to enhance oxygen absorption.

#Some specific examples of oxygenation applications are worthy of discussion. Odors at aerobic wastewater treatment facilities are associated with the inability to maintain sufficient levels of dissolved oxygen (“D.O.”). In the absence of sufficient D.O., nitrates are reduced to N2 gas. In the absence of both D.O. and nitrates, strongly reducing conditions develop and sulfates are reduced to H2S, also known as “rotten egg gas”. This process can occur in any aquatic system where the oxygen demand exceeds the D.O. supply.

#FIG. 1 shows a schematic diagram of one embodiment of an aeration system of the PRIOR ART.

#FIG. 2 shows a schematic diagram of one embodiment of a gas transfer system according to the present invention having a regenerative turbine direct coupled to the feed pump of the system.

#FIG. 3 shows a schematic diagram of a second embodiment of a gas transfer system according to the present-invention having a regenerative turbine driving an electrical generator.

#Referring now to FIG. 1, there is shown a schematic view of an aeration system of a prior art system. As previously discussed, in the embodiment of FIG. 1, prior art system 10 includes reactor 12, water (liquid) feed inlet 14, feed pump 16 for moving water (liquid) from feed inlet 14 into reactor 12, O2 (gas) feed inlet 18 for introducing O2 into reactor 12, outlet 20 for transferring liquid (water) having O2 (gas) dissolved therein, and throttle 22 used to maintain pressure in reactor 12.

#FIG. 2 shows a schematic view of one embodiment of a gas transfer system according to the present invention having a regenerative turbine directly coupled to the feed pump of the system. Like the embodiment of FIG. 1, system 30 of FIG. 2 includes reactor 32, liquid inlet 34, feed pump 36, O2 (gas) feed inlet 38, and outlet 40. Instead of a throttle at outlet 40, system 30 of FIG. 2 includes regenerative turbine 42 directly coupled to feed pump 36 by shaft 44. Shaft 44 is a common shaft rotated during operation of both feed pump 36 and regenerative turbine 42.

#In this embodiment, and the embodiments of FIG. 3, FIG. 4, and FIG. 5, feed pump 36 may comprise an axial flow, Kaplan, or centrifugal pump, such as manufactured by Flygt or Johson Pump. Regenerative turbine 42 (and the regenerative turbines of FIGS. 3, 4, and 5) may comprise an axial flow, a Kaplan turbine, or centrifugal pump, such as manufactured by Cargo-Kraft or Thomson & Howe. Gas inlet 38 may be connected to a pulsed swing absorption oxygen generator or a liquid oxygen vaporizer (not shown) to force the desired gas into reactor 32.