Integrated gas sparger for an immersed membrane
A gas sparger produces an intermittent flow of bubbles even if provided with a continuous gas flow. The sparger has a housing to collect a pocket of gas and a conduit to release some of the gas from the pocket when the pocket reaches a sufficient size. The housing is integrated with the potting head of a module. The conduit passes through the potting head.
1. A combination of a membrane module and an apparatus for providing gas bubbles in a liquid comprising,
a) a housing defining a chamber and having an opening below the chamber allowing communication between the inside of the chamber and the outside of the chamber; and,
b) a conduit extending from a first opening to a second opening, wherein the first opening is inside of the chamber and the second opening is outside of and above the chamber, the conduit having a first portion that extends downwards from the first opening to a low point of the conduit and a second portion that extends upwards from the low point of the conduit to the second opening in a direction from the first opening to the second opening,
wherein,
c) the chamber is adapted to hold a pocket of the gas above an interface between the gas pocket and the liquid, the interface having a variable elevation ranging from at least a lower boundary of the first opening in the conduit to an upper boundary of the low point of the conduit;
d) the membrane module comprises a permeate cavity below a potting head of the membrane module;
e) the second portion of the conduit passes through the potting head and the permeate cavity;
f) the conduit having no third opening or tube in communication with the liquid outside of the chamber below the interface; and,
g) wherein the potting head is a block of hardened resin into which membranes of the membrane module are potted.
2. The combination of claim 1 , wherein the second opening of the conduit is at or above the top of the potting head.
3. The combination of claim 1 further comprising a gas supply conduit extending horizontally below the chamber and having an outlet to discharge gas into the chamber.
4. The combination of claim 1 further comprising a cap or diffuser above the potting head and over the second opening of the conduit.
5. The combination of claim 1 wherein the second opening has an area of 1-10 square cm.
6. The combination of claim 1 wherein the cross-sectional area of the second opening of the conduit is less than the horizontal cross-sectional area of the chamber by a factor of at least 10.
7. The combination of claim 1 having only one second opening.
8. The combination of claim 1 having a plurality of the potting heads, each with an associated housing and conduit, and further comprising a gas supply conduit extending horizontally below the chambers of the housings and having an outlet to discharge gas into each chamber.