Quote:
Originally Posted by Hugh R
I did an environmental due diligence for insurance on the De-Sal Plant in downtown Santa Barbara 20 years ago, it was pretty interesting. The City/County is now talking about reviving that plant. They ran an intake pipe inside an old sewage pipe that went a mile or two out into the ocean.
If you think about it, De-Sal plants make a lot of sense with nukes. They need cooling water, seawater turns to steam which is pure water vapor. Put in another seawater cooling loop and turn the steam into condensed fresh water.
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Using heat exchangers to boil sea water is one heck of a challenge. The salts tend to lay down and foul the exchangers in no time flat. That causes hot spots, corrosion, and loss of heat transfer.
The trick is to control the heat and pressure so the water flashes to steam at exactly the right moment and place so you can seperate the salts and dispose of them, but it's much harder than it sounds.
Standard rule of thumb is anything higher than a 250 F delta P requires purified water, 150 to 249 can use chemically treated treated (clean) water.
Some nuke plants use sea water as a coolant, but it's a three stage process from core to condensor.
The core heats pure water to turn it to steam.
That water flows through a heat exchanger where it transfers heat to purified water on the other side of the exchanger and turns it into steam but has no physical contact to prevent contamination.
That steam flows through the turbines where it gives up it's heat, and finally exits the low stage turbines into a condensor.
At that time it is technically still steam but it's around 140 degrees F because its under about 28 inches of mercury worth of vacuum created by the condensor.
Sea water flows through the other side of the condendor where it only has to reduce the temperature about 60 degrees and never goes through a phase change.
it still requires a great deal of backflusing, travelling screens, and other maintenance to keep that condensor relatively clean.