Stripping of contaminants from water

A process for stripping volatile contaminants from a liquid stream in which the contaminants are dissolved, comprising the following steps in the order recited:

• utilizing a gas-inducing mixer-injector having a inlet port, a tapered constricting section, a substantially cylindrical throat section, an enlarging section and an outlet port in that order, and an injector port in said throat section, said sections being so proportioned and arranged as to create a reduced pressure in said throat when said liquid supply stream flows from inlet port to outlet port, flowing said liquid supply stream through said injector, said mixer-injector drawing a stripping gas into said liquid supply stream through said injector port to form a mixed stream of liquid with it contaminant and bubbles of said stripping gas, at least some of said contaminants entering the stripping gas in said bubbles;
• passing said mixed stream to a centrifugal degassing separator;
• said degassing separator having a drain port, an inner separator chamber with a cylindrical wall and a nozzle proportioned and arranged so as to discharge said mixed stream tangentially along said cylindrical wall to create a swirling centrifugal flow from the nozzle toward the drain port, a perforated gas separator tube extending centrally in said chamber to receive said separated gas from said bubbles which separated gas has been centrifugally separated from the liquid, and a gas outlet port opening into said separator tube to receive said separated gas, said liquid remaining after separation of the gas being processed liquid;
• utilizing a vacuum pump at said gas outlet port, withdrawing said separated gas from said separator tube for disposition after it exits from the vacuum pump;
• and
• utilizing suction apparatus having an inlet connected to said drain port, said suction apparatus adapted to exert suction at said drain port to withdraw said processed liquid and separate said processed liquid from the drain port while maintaining that portion of the flow path of liquid and gas which extends from the throat of the injector to the gas outlet port and to the drain port of the separator at sub-atmospheric pressure.

A system for stripping volatile contaminants from an incoming liquid stream from a source of said liquid to produce an outgoing stream with a reduced concentration of said contaminant, said system comprising:

• a cavitating type mixer-injector comprising a body, said body having a passage therethrough with an inlet port, an outlet port, a tapered constricting section, a generally cylindrical throat section, and a tapered enlarging section in that order between said inlet port and said outlet port, an injector port through said body opening into said throat section, said constricting section and throat section being so proportioned and to form a local region of reduced pressure in said throat;
• said injector port being adapted to receive stripping gas from a source of stripping gas;
• a centrifugal de-gasser separator having an inlet port in fluid communication with the outlet port of said injector, a drain port to release liquid from which stripping gas and some contaminant has been separated by said separator, and a gas outlet port to release gas that has been separated from the stream by said separator, said separator comprising a case having an inlet port and forming an inner separator chamber with a cylindrical wall having a linear axis, a nozzle in said inlet port directing flow of liquid in a tangential path on said cylindrical wall whereby to produce a whirling stream flowing toward said drain port, a gas separator tube extending axially and centrally in said chamber from said gas outlet port, said separator tube being hollow and having a plurality of perforations therethrough along its length, there being substantial annular space between said separator tube and said cylindrical wall;
• a conduit conveying fluid from said mixer injector to said inlet port of said separator;
• a gas outlet valve connected to said gas outlet port;
• a vacuum pump connected to said gas outlet valve to expel gas from said separator;
• suction apparatus drawing liquid from said drain port, said system being adapted for operation at sub-atmospheric pressures by said suction apparatus and being closed between the throat section of the mixer-injector and the drain port and gas outlet port of the separator except at the injector port of said injector.