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Waste heat evaps on yachts

Discussion in 'Technical Discussion' started by Dan Evans, Oct 22, 2009.

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  1. Dan Evans

    Dan Evans Senior Member

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    Hi everyone,
    Does anyone know of yachts that use waste heat evaps to make water? I have been wondering for a while if this is a technology that has reached the yachting industry but have not been able to find any mention of it on this forum. Do the evaps just not work as well when scaled down from ship size to yacht size?

    Thanks for any input/examples

    Dan
  2. 'RoundTheHorn

    'RoundTheHorn Senior Member

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    Alfa Laval

    I don't know if this has reached any yachts. They would need to be fairly large I believe to support technology like this, but Alfa Laval does make such units for large ships and offshore rigs.

    Desalt fresh water generators
  3. Dan Evans

    Dan Evans Senior Member

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    I have worked with the Alfa Laval evaps but that was on a 25,000 hp ship. Alfa Laval doesnt make any scaled down models. Obviously their equipment isnt made for yachts but I was thinking that it may be possible to scale it down since, even though yachts produce less BTUs, they consume less water.
  4. Marmot

    Marmot Senior Member

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    They work just fine. I have used the Maxim units referenced in the link below on yacht sized vessels. They ran off generator coolant and were great little units. They knew when there was enough heat to make water and when there wasn't and sent good water to the tanks and bad water overboard.

    http://www.maximevaporators.com/products.html

    There are also several manufacturers of plate type evaps like the Nirex distillers mentioned in the previous post but I have no experience with their smaller units, though they are available down to 4 or 5 hundred gallons per day. The large ones are fantastic, easy to use, require little service, come online quickly and are easy to automate.

    If you consider the operational pattern of most yachts, there are not many places a low temperature evaporator should be used. The boat spends most of its life floating in sewage at a dock and rarely goes far enough offshore or long enough to get away from contaminated feedwater. While an RO unit "filters" out bacteria and even most viruses, the low temperature process of a distiller makes incredibly pure water from a chemical standpoint but it can carry a load of nasty organisms from the feedwater and requires very good post-treatment to ensure safe drinking water.

    If I were outfitting a yacht for an extended world cruise I would seriously consider an evaporator or two in addition to an RO. After all, the energy to run it is "free" and it doesn't need the TLC and expensive consumables an RO demands.
  5. K1W1

    K1W1 Senior Member

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    Hi,

    I imagine you must be bored and trying to see if there is anyone else awake on here with that statement:D

    While I agree there is no additional fuel cost with the use of this "energy" it has actually cost the ship Owner and or operator money to produce and if it were not used for this would be pumped over the wall anyway.

    This therefore could be looked at as a form of recycling on yachts..... it has to start somewhere.
  6. Marmot

    Marmot Senior Member

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    Woke you up did it?

    No additional cost because the heat was going over the side anyway, and the cost of fuel to make electricity to run an RO stays in the owner's pocket.

    It certainly is recycling. If we monitored energy use on yachts like we do on ships we would see the plant efficiency go up a notch when the waste heat evap was on vs the RO. That is why we use waste heat boilers to make steam to drive turbine generators, heat the hotel, and replace electricity for a number of other heating jobs. Fuel tanks hold lots of little dollar bills. Heat going up the stack or over the side is little dollar bills fluttering away. The more we capture the longer the tanks stay full.
  7. K1W1

    K1W1 Senior Member

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    Hi,

    No some nameless cretin did that with the phone at 0550 this morning so I have already been awake for a few hours getting ready to head back to the real world- If that is what I do for a living can be called.
  8. Marmot

    Marmot Senior Member

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    Hope all is as well as can be. Also hope you are stopping by on your way back.
  9. Dan Evans

    Dan Evans Senior Member

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    We ran the water through a UV light after the evap to kill the "nasty organisms."

    You are right about the pattern of where the yachts would be when they would need to use this system. It would obviously work very well with explorer yachts or any yacht that is on an extended cruise or in a non-contanimated environment (if we can still find those). The key phrase with a system like this is at no extra cost. Its about squeezing every ounce of energy out of the fuel tanks so that fuel can be used for exploring, not hotel services.

    Since green yachts are becoming more and more popular I would not be surprised to see more of these systems being used.
  10. K1W1

    K1W1 Senior Member

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    Hi,

    You would not be able to do this on a UK Flagged Vessel where UV Sterilization is only suitable for use as the water goes to the consumers NOT before it goes into the storage tanks.
  11. Dan Evans

    Dan Evans Senior Member

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    Good point, just for grins and giggles I think I would prefer to have UV treatment before and after the tanks. No bugs in the tanks, no bugs in the tap. Plus then you have a redundant system incase one UV light went out.

    Does the rule say that you CAN'T have one before the tanks or just that you must have one between the tank and consumer?

    Dan
  12. K1W1

    K1W1 Senior Member

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    Hi,

    It is not specifically banned as such, an auto chlorinator or Silver Ion treatment system must be fitted to all new ones since 1986 or if your boat is older and doesn't have one fitted a regular chlorine dosing routine must be applied.