Ventilation devices and methods
Devices are provided for ventilating and/or removing volatile chemicals from liquid (e.g. water) stored in a liquid-containing storage tank (e.g. water-storage tank). The devices include a first fluid flow path that is physically isolated from a second fluid flow path and a convection device for moving a first fluid along the first fluid flow path toward at a desired destination and for exhausting the first fluid at the desired destination at a desired velocity. Methods are also provided for ventilating and/or removing volatile chemicals from liquid (e.g. water) stored in liquid-containing storage tanks (e.g. water-storage tanks). The methods involve blowing a first fluid through a ventilation device into a liquid-containing storage device at a velocity sufficient to achieve a desired mass transfer rate of volatile chemicals from the liquid in the liquid-containing storage device to air in the headspace and flowing the contaminated air back through the ventilation device.
1. A device for removing volatile chemicals from stored liquid in a liquid-containing tank, comprising:
a. a housing;
b. an air intake system at least partially within the housing comprising an outside air entry port for allowing outside air to enter the device; an outside air exit port for allowing the outside air to exit the device; and wherein the air intake system is configured for moving outside air through the housing from the outside air entry port to the outside air exit port along an outside air flow path such that the outside air exits from the housing at a desired velocity and in a desired direction; and,
c. a volatile chemical exhaust system also at least partially within the housing comprising a volatile chemical entry port to allow volatile chemicals to enter the device; a volatile chemical exit port to allow volatile chemicals to exit the device; and wherein the volatile chemical exhaust system is configured to move volatile chemicals through the housing from the volatile chemical entry port to the volatile chemical exit port along a volatile chemical flow path, which is physically isolated from the outside air flow path;
wherein: the device is configured such that a stream of outside air entering the device through the air intake system and a stream of air contaminated with volatile chemicals exiting the device from the volatile chemical exhaust system are not coplanar; the air intake system further comprises a blower device which facilitates movement of outside air from the outside air entry port through the housing and to the outside air exit port; and, the outside air exit port and the volatile chemical entry port are in a concentric configuration, with the outside air exit port located interior to the volatile chemical entry port, and further wherein the device also comprises a first conduit attached to an exhaust end of the blower device which protrudes outside the housing and defines the outside air exit port, and a second conduit with a larger diameter than the first conduit which also protrudes outside the housing but to a lesser degree than the first conduit.
2. A device according to claim 1 wherein the desired velocity and the desired direction are chosen to achieve a desired mass transfer rate of outside air with volatile chemicals at an air-liquid interface in the liquid-containing tank when the housing is operatively attached to the liquid-containing tank.
3. A device according to claim 1 , wherein the desired direction ranges from about 30 degrees to about 90 degrees relative to an air-liquid interface in the liquid-containing tank when the housing is operatively attached to the liquid-containing tank.
4. A device according to claim 3 , wherein the desired direction is substantially perpendicular to the air-liquid interface in the liquid-containing tank when the housing is operatively attached to the liquid-containing tank.
5. A device according to claim 1 , wherein the outside air enters the device horizontally and the air contaminated with volatile chemicals exits the device vertically.
6. A device according to claim 1 , wherein the blower device is a centrifugal fan.
7. A device according to claim 1 , wherein the housing is configured to sit on a top surface of the liquid-containing tank and to provide an outside air flow path in which the outside air moves into the housing along a substantially horizontal path and exits the housing into the liquid-containing tank along a substantially vertical path.
8. A device according to claim 7 , wherein the housing further comprises a rain shield.