Has anyone made

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dougg

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Has anyone made there own watermaker?
If so I would be interested which pump they have used.
Im looking to make / assemble one using a 12 volt high pressure pump.
Idealy i would like to limit it to a draw of around 25 amps.
 
Water maker

As I understand it modern water makers use a pump system which can recover the energy from the exit pressure water to augment the inlet pressure so reducing energy enormously.
This might dictate something sophisticated in the way of pumps. Am I right and can anyone explain further.
olewill
 
CAT pumps are the standard. However William H posted aboce 'As I understand it modern water makers use a pump system which can recover the energy from the exit pressure water to augment the inlet pressure so reducing energy enormously'.

Not heard of that but it sounds good, perhaps prohibitively expensive.
 
KellysEye said:
Not heard of that but it sounds good, perhaps prohibitively expensive.
Click to expand...

I was going to say much the same thing as Olewill. I believe the energy-recovery pump is patented by one of the watermaker manufacturers; perhaps others license the patent in order to use the idea?

Essentially, under the old-style system, the waste brine is still under quite high pressure. That is a store of energy, which would be wasted if you just squirted it into the sea. The energy-recovery pumps instead use it to help drive the input pump. Not sure of the mechanical details.

It's the energy recovery that first made hand-pumped watermakers practical; used in powered ones it reduces the amount of electricity consumed.

Pete
 
If you make your own waternaker its not possible to make an energy recovery model. The energy recovery pumps are only made by a few companies and they will not sell you the high pressure pump, because they dont want homemade watermakers to made with this technology.

Without the energy recovery you will need more than 25A.

The best policy without energy recovery is to make a high capacity watermaker that can produce a couple of days of water in only an hour or so. The watermaker then is only run when the main engine (with big alternators) or generator is run.

With energy recovery its practical to run the watermaker from solar or wind power so a smaller capacity model that’s run for a few hours is often the best option.
 
The smallest DC Echotech needs a 1/4 kilowatt to run it ( 20a at 12.5v )

The smallest engine driven one pumps twice as much water so 1/2 kw? from the main engine.

Echotech states in their literature 'For economical maintenance ECHOTec does not use proprietary components that bound you to purchase expensive consumables only available from the original manufacturer. Standard filters, chemicals and membranes can be obtained anywhere.'

So for your money ( $4500 - $5000 w/o installation ) you get a high pressure pump, a clutch, hoses, prefilter, panel and a 40" r/o chamber.

Back to the homebuild version!

Cat pumps http://www.catpumps.com/ are possibly the top manufacturer of triple reflex stainless steel pumps
 
I made my own mains driven using the Wanner Hydra-cell pump as there was a supplier local to me.

Wanner also do the same pump that can be engine driven.

No pressure recovery as has been said the membrane needs flushing more which negates the energy saved by having to use more of the made fresh water to clean the membrane.

I have an article sent to me by Stingo (John Perry) and if any one would like a copy just E-Mail me (see profile).
 
When I was at sea on merchant ships we made water using vacuum systems with low grade heat. I'm just wondering why this system has never been utilised on boats. I guess it's a power thing.
 
On the other end of the scale

We have a desalination plant nearby. Using RO and the energy recovery pumps for domestic water supply.
Ironically now the plant is built and another on the way we have had plenty of rain this season.
The plant was intended to be powered by wind generators but that has not happened so more coal in the power stations... olewill in the antipodes
http://www.watercorporation.com.au/d/desalination.cfm
 
We have an HRO watermaker with an "energy transfer device" that boosts the 150 psi produced by the pump to 600 psi from the ETD which is separate unit with a couple of pistons that pulse back and forth to amplify the original pump pressure.

The large pump has a small head with carbon blades and a carbon yoke which is very easy to damaged. We had a faulty mesh filter and particles got through that scored the vanes and the pressure dropped dramatically. A new pump head was £850!!!!

At 25 amps DC this system produces 70 litres an hour.
 
daveyw said:
When I was at sea on merchant ships we made water using vacuum systems with low grade heat. I'm just wondering why this system has never been utilised on boats. I guess it's a power thing.
Click to expand...

Because it is very inefficient unless you happen to have a source of low grade heat available, and don't care how much of it you use. Reverse Osmosis is far more efficient.
 
daveyw said:
When I was at sea on merchant ships we made water using vacuum systems with low grade heat. I'm just wondering why this system has never been utilised on boats. I guess it's a power thing.
Click to expand...

I was interested in using vacuum and waste engine heat to distill fresh water but then a diesel engine doesn't develop manifold vacuum worth talking about so it would mean fitting a vacuum pump. Once you've done that you may as well have fitted a pressure pump and stuck with more available systems.

Nice system here but, manufactured out of titanium it's going to make a traditional watermaker seem cheap by comparison I suspect.
 
Basically distillation has to provide latent energy of vaporization of the water. RO doesn't. Water has a very high latent heat of vaporization; much more than most liquids. Lowering the pressure reduces the temperature, but doesn't reduce the overall energy budget - low pressure means you can use low grade "waste" heat, but doesn't reduce the overall amount of energy required by very much. So RO is intrinsically much more efficient than distillation. AFAIK, RO is the process used in large-scale desalination plants.

Similarly, it is technically feasible to purify water by fractional crystallization - this happens on a vast scale in the polar regions, where sea-ice is pure water; once it has had time to expel salt pore water and so on, old sea-ice is a good source of fresh water. But for a process on board ship, it hits the same barrier - the latent energy of fusion of water is very high, so there is a big energy barrier in the way.

Non boating anecdote! Many years ago, I worked in a research laboratory that had all sorts of interesting experimental gear, including a fractional crystallization rig that could operate on batches of liquid in the region of many gallons, and over a wide range of temperatures. The story goes that one Christmas, the lab technicians ran a barrel of beer through it. The crystallization rig removed water, leaving something that was about 96% alcohol! I'm told - it happened before my time - that it was good stuff :)

Shackleton is also reputed to have done the same while in Antarctica - left a barrel of beer outside, and removed the ice as it formed.
 
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DIY

Rogershaw said:
I made my own mains driven using the Wanner Hydra-cell pump as there was a supplier local to me.

Wanner also do the same pump that can be engine driven.

No pressure recovery as has been said the membrane needs flushing more which negates the energy saved by having to use more of the made fresh water to clean the membrane.

I have an article sent to me by Stingo (John Perry) and if any one would like a copy just E-Mail me (see profile).
Click to expand...

Could you comment on cost, ease of use and production ??
 
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