Process and apparatus for measuring dissolved gas

Abstract

There is disclosed a process and apparatus for measuring the amount of a dissolved gas in a liquid wherein the device used to measure the gas is not immersed in the liquid and wherein there is no requirement that a sample of the liquid be removed from the main body of the liquid to be tested. A vertical zone is provided in the body of liquid which is to be measured for the amount of gas contained in the liquid, such as in the aeration tank in a sewage treatment system. The zone is at least partially open at the lower end so that it is in communication with the body of liquid and is closed to contact with the body of liquid on the sides. A gas is passed into the lower portion of the zone and a gas-lift effect is created in the zone. Gas is recovered at the upper portion of the zone and is returned to the lower portion of the zone, thereby creating a closed recirculating gas system -- i.e., the system is closed to the atmosphere and to the liquid outside of the zone. The gas-lift effect causes liquid to continuously overflow the top of the zone from which it is returned to the body of liquid outside of the zone and additional liquid enters the lower portion of the zone from the body of liquid outside of the zone. Recirculation of the gas is continued to establish an equilibrium between the recirculating gas and the liquid in the zone as to the dissolved gas to be measured. When this equilibrium has been reached, the amount of dissolved gas which has been extracted into the recirculating gas is measured by a gas measuring means which is not in contact with the liquid containing the dissolved gas.

Dependencies are inferred from the claim text.