US 3,945,918 A · Methods and apparatus for treating a liquid with a gas

Abstract

Methods and apparatus for treating a liquid with a gas wherein a liquid feed is introduced to the initial stage of a multi-stage device for dissolving the gas in the liquid. Efficient mass transfer is achieved by effecting a gas-liquid counter flow in serial stages of the dissolution device. The effluent from the dissolution device exhibits a relatively high dissolved gas concentration which gas is subsequently consumed by the liquid in a reaction tank. A liquid recycle line is provided for returning and combining treated liquid with the incoming feed thereby enabling further dissolution of the gas in the liquid. In the course of treating wastewater with ozone, a flotation clarifier may be provided with the initial stage of the dissolution device to enable the surface coagulation of impurities in the wastewater feed. The coagulants may be skimmed prior to introducing wastewater into subsequent stages of the dissolution device, thereby substantially reducing the ultimate ozone demand of the wastewater.

Claims20

Dependent claims

A method of treating a liquid exhibiting a demand for a gas comprising the steps of introducing said liquid into the initial stage of a multistage dissolution device, passing said liquid by gravity generally downwardly from one stage to the next through all stages of the device, introducing said gas into the final stage of the device to thereby establish a gas-liquid counterflow through said stages and to dissolve at least a portion of said gas in said liquid, subjecting said liquid to a confined gravitational free fall through said gas in a fall zone in at least one of said stages to create a high liquid-gas turbulence in said zone thereby effecting a mass transfer of at least a portion of said gas into said liquid, disentraining undissolved gas from said liquid after passage thereof through said zone, and passing said disentrained gas from said space generally upwardly to a previous stage of said device by the buoyancy of said gas;

conducting the effluent of said device to a reaction tank wherein dissolved gas is consumed in said liquid;
recycling at least a portion of the liquid in said reaction tank to the initial stage of the dissolution device to enable further dissolution of said gas in said liquid;
and discharging treated liquid from said reaction tank.

Apparatus for treating a liquid exhibiting a demand for a gas comprising:

multistage dissolution means having a plurality of serially arranged dissolution stages each of which is at a greater elevation than the following stage such that a liquid is conducted downwardly and serially therethrough;
inlet means for introducing said liquid into the initial stage of said dissolution means;
means for establishing a gas-liquid counterflow through all stages of said dissolution means thereby dissolving at least a portion of said gas in the liquid in each of said stages at least one of which stages comprises means for subjecting said liquid to a gravitational fall through said gas to produce a high liquid-gas turbulence whereby a mass transfer of a portion of said gas into said liquid is effected, means for disentraining undissolved gas from said liquid upon passage thereof through said fall means;
and means for passing said disentrained gas to the preceding stage of said dissolution means;
a reaction tank adapted to receive liquid from the last stage of said dissolution means such that said dissolved gas is substantially consumed by said liquid in said reaction tank;
and means for recycling liquid in said reaction tank to said initial stage of said dissolution means to enable further dissolution of said gas in said liquid.

3 more elements

Apparatus for dissolving a gas in a liquid comprising a plurality of substantially overlying dissolution stages arranged to define a generally downward liquid flow path therethrough, each of said stages having a gas accumulation space therein and at least one of said stages comprising a static gas-liquid mixing device having a gravitational fall zone wherein said liquid is subjected to a free fall through said gas thereby promoting a high liquid-gas turbulence in said zone and the dissolution of at least a portion of said gas in said liquid, liquid accumulation means adapted to receive liquid passing through said fall zone and gas entrained in said liquid, gas accumulation means overlying said liquid accumulation means and interconnection means for recycling gas from said gas accumulation means to said fall zone with the uppermost portion of each fall zone disposed in communication with the gas accumulation space in the immediate overlying dissolution stage;

and means for introducing said gas under pressure into the lowermost one of said stages such that said gas flows in counterflow relationship to said generally downward liquid flow through successive ones of said dissolution stages.

Dependencies are inferred from the claim text.

Methods and apparatus for treating a liquid with a gas

Life of this patent

Methods and apparatus for treating a liquid with a gas

Life of this patent

Abstract

Claims20