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Free water

 Power station cum desalination plant
 
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Have a power station which uses a steam-powered turbine draw water from the sea to drive its turbines. After the steam condenses having done its job, it gets pumped into the water supply. Googling shows that the idea is baked in one form or another, but usually the power and desalination units are housed separately. Is it possible, that after the steam has gone through the turbines, we condense it, and then pump it into the water supply, hence doing away with the desalination unit?
—LoneRifle, Mar 10 2003

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       I'm no expert in power generation, but I'd assume that the cooling water is not part of the closed loop steam generation cycle, which is very sensitive to contaminants. Cooling water from the sea would never be boiled off into steam, thus ruining your plan.
—pluterday, Mar 10 2003
   

       //cooling water//   

       ???   

       I was not referring to cooling water, what i was referring to instead, was to have the coal (or oil or gas) power station draw seawater to convert to steam to drive its turbines. Once the steam has passed through the turbines, it is condensed and the water chanelled into the local water supply. I'm sorry if I've confused anyone; appropriate changes have been made to the idea.   

       But as pluterday mentioned, the generation cycle is very sensitive to contaminants, eliminating the use of seawater in the first place.
—LoneRifle, Mar 10 2003
   

       I'm voting for this, just 'cause it strikes me as one of those cleverly obvious things worth more exploration, although it probably won't get the praise it deserves as a real engineering idea. (hint, to get more traffic / responses, make the title a little more 'catchy').   

       Oh and, welcome to the 'Bakery and all that. If you're new to the place, the help file's on the left, worth a look if you haven't yet.   

       While pluter's right about the contamination issue in the closed loop side of the turbine cycle, I'd think that toying with the cooling water exhaust would be worth looking into, with proper filtration, or perhaps even a heat exchanger.   

       If I recall, most cooling systems don't allow the water to boil, as steam has only half the heat capacity, and system pressures are an issue. It would have to be very closely controlled, and probably not the primary cooling system, should a failure occur. But perhaps even raising a few degrees of temperature towards boiling would be worth the cost of implementation. The water could then be finalized at a regular desalination plant.
—RayfordSteele, Mar 10 2003
   

       [pluterday] is spot on. The demineralised water used in steam turbines is of extremely high quality, having been filtered, chemically treated, ion- exchanged and forced through expensive reverse osmosis filters by high pressure pumps, etc. This water is fantastically pure and priced accordingly.   

       However, the waste heat from the generation process can be reclaimed and used to distil water (cogeneration). Some countries have desalination plants that use this technology.   

       Perhaps you are thinking of those big steam stacks that pump out plumes of steam... well, that's lower quality cooling water and much of the water does condense back and is recycled. The rest is a matter of economics.
—FloridaManatee, Mar 10 2003
   

       //The demineralised water used in steam turbines is of extremely high quality, having been filtered, chemically treated, ion- exchanged and forced through expensive reverse osmosis filters by high pressure pumps, etc. This water is fantastically pure and priced accordingly.//   

       My intention is to pump THIS water into the supply... I'm very sorry, I've obviously not been clear....   

       thank you for the welcome, [RayfordSteele]. As I've seen before I registered, this place isn't particularly kind to newbies, so I was apprehensive when posting this...   

       By the way, what exactly is inside the croissant at the top left corner? I never managed to figure it out...
—LoneRifle, Mar 11 2003
   

       Could there ? Really ? Well, you learn something new every day. I think someone should tell the British Government about this one.   

       These issues ..... serious, are they ?
—8th of 7, Mar 11 2003
   

       //this place isn't particularly kind to newbies//
Sure it is - just gotta be someone like your elf, is all.
per pluterday's response - best way I can vaguely recall to purify water on this dual porpoise plan is to use it as if it were irrigating, like a rain-bird sprinkler - in a very cold place. The water freezes, but loses it's salinity in the process. Kind of like an ex-girlfriend of mine.
—thumbwax, Mar 11 2003
   

       //Surely the waste steam from the cooling loop would be better for this purpose?//   

       going by pluter, RS and the rest, apparently water in the cooling loop does not boil off into steam, or at least should not anyway, i gather...?
—LoneRifle, Mar 11 2003
   

       // As I've seen before I registered, this place isn't particularly kind to newbies, so I was apprehensive when posting this... //   

       There's the single greatest reason why that 'Newbies and this place" thread should be deleted immediately.
—waugsqueke, Mar 11 2003
   

       //The plume of steam you see in the cooling tower? It has to come from somewhere, and it's not the closed loop.//   

       Okay. Never seen a cooling tower, or a real power plant for that matter......
—LoneRifle, Mar 11 2003
   

       In any steam turbine power plant, there are at least two loops, in the most basic sense. There's the highly purified stuff that goes through the multi-stage turbines / reactor core / whatever, and there's the cooling loop, which is a separate line that uses a heat exchanger to bleed off the waste heat from the turbine loop. That second may be an open loop to a water source or a closed one, depending on the design of the plant.
—RayfordSteele, Mar 11 2003
   

       Rayford's got it. That plume of steam is from the dirtiest stream of water in the process. Often that water is raw, right out of the nearby river or well, and can even be a third loop as follows:   

       First loop: VERY clean chemically treated water is boiled in steam generator/boiler, steam pushes turbine, steam is cooled back to liquid in the condensor by passing heat to the second loop, water is pumped back to boiler.   

       Second loop: water is heated (but not to boiling) by the steam from the first loop, gets pumped to the cooling tower where it is cooled by the third loop, then gets pumped again back to condenser.   

       Third loop (not really a loop at all): water is pumped into cooling tower, where it abosrbs heat from second loop by flashing to steam. Heat is carried away from system by this steam.   

       The water (in the first and second loops) that is treated at great expense is carefully kept in sealed, closed loops. We try to keep those closed loops as leak-proof as possible. Maintaining the chemistry is an art, and creating makeup water is too. In fact, the chemicals used to prevent this water from corroding the turbine and boiler render it undrinkable.   

       That said, welcome to the kitchen.
—gardnertoo, Jul 28 2004
   

       I always thought they were almonds.
—simonj, Jul 28 2004
   


 

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