Aeration system and method

A liquid treatment plant for a two-phase, gas-liquid mass transfer process, comprising a tank for containing a liquid so as to provide a gas volume above the liquid surface, means for maintaining said liquid at a predetermined level in said tank, a circulating pump for withdrawing liquid from said tank, a liquid injector pump downstream of said circulating pump and adjacent said predetermined liquid level, said injector pump having a single nozzle opening through which only liquid from said circulating pump can pass, and an outlet spaced axially a small distance from said nozzle opening, said spacing providing an inlet through which only gas can be drawn as a result of passage of liquid through said nozzle opening and into said outlet, a substantially vertical mixing pipe extending from adjacent said predetermined level to a position adjacent the bottom of said tank, and a deflector for urging a gas-liquid stream emerging from said mixing pipe in a direction transverse to the axis thereof, a portion of said injector pump outlet adjacent said nozzle opening having a cross-sectional area of between 1.05 and 1.4 times the cross-sectional area of said nozzle opening, and the cross-sectional area of said mixing pipe being between 4 and 11 times the cross-sectional area of said nozzle opening.

A method of operating a liquid treatment plant for a two-phase, gas-liquid mass transfer process, comprising maintaining said liquid at a predetermined level in a tank so as to provide a gas volume above said liquid surface, withdrawing liquid from said tank by means of a circulating pump, passing the liquid discharged by said circulating pump through the nozzle of an injector pump having an outlet axially spaced from said nozzle and also having an inlet passage communicating with the nozzle-outlet spacing and through which only gas can be drawn as a result of passage of said liquid through said nozzle to said outlet, passing the combined liquid and gas successively through said outlet and through a substantially vertical mixing pipe which communicates with said outlet and extends from adjacent said predetermined level to adjacent said tank bottom, deflecting the gas-liquid stream emerging from said mixing pipe in a direction transverse to the axis thereof, the injector pump outlet having a cross-sectional area of between 1.05 and 1.4 times the cross-sectional area of the nozzle thereof, and the cross-sectional area of said mixing pipe being between 4 and 11 times the cross-sectional area of said nozzle, and maintaining the delivery head of said circulating pump at between 17% and 30% of the depth of the bottom of said mixing pipe below the surface of said liquid.

A method of operating a liquid treatment plant for a two-phase, gas-liquid mass transfer process, comprising maintaining said liquid at a predetermined level in a tank so as to provide a gas volume above said liquid surface, withdrawing liquid from said tank by means of a circulating pump, passing the liquid discharged by said circulating pump through the nozzle of an injector pump having an outlet axially spaced from said nozzle and also having an inlet passage communicating with the nozzle-outlet spacing and through which only gas can be drawn as a result of passage of said liquid through said nozzle to said outlet, passing the combined liquid and gas successively through said outlet and through a substantially vertical mixing pipe which communicates with said outlet and extends from adjacent said predetermined level to adjacent said tank bottom, deflecting the gas-liquid stream emerging from said mixing pipe in a direction transverse to the axis thereof, the injector pump outlet having a cross-sectional area of between 1.05 and 1.4 times the cross-sectional area of the nozzle thereof, and the cross-sectional area of said mixing pipe being between 4 and 11 times the cross-sectional area of said nozzle, and maintaining the delivery head of said circulating pump at between 0.7 and 1.4 meters of the liquid being pumped.

A method of operating a liquid treatment plant for a two-phase, gas-liquid mass transfer process, comprising maintaining said liquid at a predetermined level in a tank so as to provide a gas volume above said liquid surface, withdrawing liquid from said tank by means of a circulating pump, passing the liquid discharged by said circulating pump through the nozzle of an injector pump having an outlet axially spaced from said nozzle and also having an inlet passage communicating with the nozzle-outlet spacing and through which only gas can be drawn as a result of passage of said liquid through said nozzle to said outlet, passing the combined liquid and gas successively through said outlet and through a substantially vertical mixing pipe which communicates with said outlet and extends from adjacent said predetermined level to adjacent said tank bottom, deflecting the gas-liquid stream emerging from said mixing pipe in a direction transverse to the axis thereof, the injector pump outlet having a cross-sectional area of between 1.05 and 1.4 times the cross-sectional area of the nozzle thereof, and the cross-sectional area of said mixing pipe being between 4 and 11 times the cross-sectional area of said nozzle, and maintaining the delivery head of said circulating pump at between 1/1.5 and 1/10 of the length of said mixing pipe.