Desalination system
A desalination system in the form of a submerged gas evaporator that includes a vessel, a gas delivery tube partially disposed within the vessel to deliver a gas into the vessel and a fluid inlet that provides a fluid to the vessel at a rate sufficient to maintain a controlled constant level of fluid within the vessel. A weir is disposed within the vessel adjacent the gas delivery tube to form a first fluid circulation path between a first weir end and a wall of the vessel and a second fluid circulation path between a second weir end and an upper end of the vessel. During operation, gas introduced through the tube mixes with the fluid and the combined gas and fluid flow at a high rate with a high degree of turbulence along the first and second circulation paths defined around the weir, thereby promoting vigorous mixing and intimate contact between the gas and the fluid. This turbulent flow develops a significant amount of interfacial surface area between the gas and the fluid resulting in a reduction of the required residence time of the gas within the fluid to achieve thermal equilibrium which leads to a more efficient and complete evaporation. Additionally, vapor exiting the submerged gas evaporator is condensed in a condensing unit thus precipitating vapor into a liquid for removal.
1. A method of removing salt from an evaporative fluid in a desalination system evaporator having a weir disposed within an evaporator vessel, the weir defining first and second volumes within the evaporator vessel and a gas delivery tube extending into the evaporator vessel into the first volume, comprising:
supplying an evaporative fluid to the evaporator vessel at rate sufficient to maintain an evaporative fluid surface level in the evaporator vessel near or above a first end of the weir;
providing gas through the gas delivery tube to force the gas through an exit in the gas delivery tube to cause mixing of the gas and the evaporative fluid within the first volume by creating a circular flow of evaporative fluid from the first volume around the first end of the weir into the second volume and from the second volume around a second end of the weir and into the first volume;
removing exhaust gases through an exhaust stack in the evaporator vessel; and
condensing evaporative fluid vapor contained within the removed exhaust gases.
2. The method of claim 1 , further including removing evaporative fluid with suspended solid particulate from the evaporator vessel.
3. The method of claim 1 , wherein providing the gas causes the evaporative fluid to at least partially evaporate.
4. The method of claim 1 , wherein condensing the evaporative fluid vapor includes supplying the evaporative fluid vapor to a condensing unit.
5. The method of claim 4 , wherein the condensing unit includes a condensing vessel having a cooling fluid inlet port, a cooling fluid outlet port, and a condensing tube at least partially disposed below an operating level of cooling fluid in the condensing vessel.
6. The method of claim 5 , further comprising pumping evaporative fluid vapor through the condensing tube.
7. The method of claim 6 , further comprising removing condensed evaporative fluid from removal valves in the condensing tube.
8. The method of claim 4 , further comprising maintaining an operating level of cooling fluid in the condensing vessel.
9. The method of claim 1 , wherein gas is supplied to the delivery tube under positive pressure.
10. The method of claim 1 , wherein gas is supplied to the delivery tube under negative pressure.
11. The method of claim 1 , wherein gas is supplied to the delivery tube at a rate from about 1,000 acfm to about 18,000 acfm.
12. The method of claim 1 , further comprising removing condensed evaporative fluid from the evaporator vessel.
13. The method of claim 1 , wherein the evaporative fluid is ocean water.
14. The method of claim 1 , wherein ocean water is used both as an evaporative fluid and a cooling fluid.
15. The method of claim 1 , further comprising heating the gas prior to providing the gas to the gas delivery tube.
16. The method of claim 15 , wherein the gas is heated by solar energy.
17. The method of claim 1 , wherein the evaporator vessel includes a baffle disposed above the weir.
18. The method of claim 17 , wherein the baffle is disposed approximately 8 inches above the weir.
19. The method of claim 1 , wherein the gas is ambient air.
20. The method of claim 1 , further comprising operating multiple desalination systems in series.