GE Merlin RO for sap???

[Gary R]

Gary in NH, would you be willing to share your design?

[Brent]

If it works I'll share the whole thing with pictures

If it flops, well .....

[Gary in NH]

Gary in NH, would you be willing to share your design?

Yes, I will get some pictures onto photobucket and give details here. It mat take a couple of days though.

Gary

[Stephen Childs]

I tested a GE Merlin RO this spring to see what one would do for a smaller maple producer. It worked great except the rated capacity dropped substantially when running sap vs. running water. Instead of a permeate flow of 20 gallons per hour, with sap I was getting between 3 and 5 gallons per hour depending on the sugar concentration of the sap. I used a flow control value and flow meter to monitor concentrate but even at the most limited concentrate flow rates I could only get the sugar content up to 5% at 60 psi. It cut my boiling time in half and saved about half the wood in my back yard with 30 taps but I was hoping it would be more effective for producers in the 100 to 150 tap size.

[brookledge]

I'm wondering if it will slow down any more as the membrane ages. But I'd bet that if you are running a pump to maintain 60psi it's got to cost more energy than you are saving or close to it.
I can see why you where disapointed. it sounded like it was a good idea back when the post first started
Keith

[Grade "A"]

Brent was saying that he was taking out around 9 gallons of water a hour out of one RO, he has two so he was taking out 18 gallons total. But he had his pump set at 80 psi. 20 psi more may not sound like alot but it could make a big difference on gph.

[Gary R]

Stephen,

Maybe PM Brent and compare notes. It seems like he did a lot of work with his Merlin's this sping. Do you have detail's on the pump's and everything else you used? Sap temperature I think is also a big reason for reduced output. I would also be concerned about cleaning and live time of membranes. But just think about the potential! A hobbyist could more than double the amount of taps for maybe $1000. That sure beats buying a bigger evaporator for $5000 and up.

Gary

PS, I wish I would have attended your maple confections workshop in PA. I heard from some attendees it was great!

[royalmaple]

Is it possible to control the Concentrate output on these machines?

If so, instead of cranking it down to see how sweet you can get it right out of the RO, open up the concentrate valve and don't try to get it in one pass. Take the concentrate and divert it back into your raw sap tank and let that run for a while. You're still removing water each minute the machine is running. Even though it might seem like your defeating the purpose. Then when the entire batch is sweet enough, run it through one more if you like what you are getting for concentrate, and send that to your head tank on the final pass. Allowing more flow from the concentrate will keep the membrane "open" much longer during your concentration cycle. I'm quite familiar with what it takes when you don't have recirculation. You can get there but takes a little ingenuity.

Without recirculation on the membranes your production will be much lower than if you had recirculation on the membranes. I don't mean recirculating the sap like I described above. I mean an actual recirculation pump attached to the membrane itself.

[Grade "A"]

I am going to try the Merlins this year. I hooking it up like royalmaple said, puting the concentrate back into my raw sap tank. It would be nice to have 8%-10% sap coming out to boil but with these ro's I don't think you can. I look at it as any water taking out is time and money saved.

[Stephen Childs]

I tried a number of things when I was testing out the merlin. My first goal was to remove as much water as possible. I obained the most water removal when I ran straight sap and didn't restrict the concentrate flow. When operating this way I was removing between 4.5 and 4.8 gallons of water per hour but when doing it this way my sugar content would only go from about 2.2 in the source sap to 3 to 3.5 in the concentrate. If I ran the concentrate back in with the source sap and recycled it, as the source sap sugar concentration increased over time the water removal rate would decrease. This was not a problem at the speed I boil (pretty slow in my restaurant pan), it just took longer to get more water out. My second goal was to have the sap as sweet as possible when added to the boiling pan. To accomplish this I had to restrict the concentrate to about 5 gallons per hour but this also slowed the water removal rate to 3 gallons per hour or less. It seemed to work best all around to recycle concentrate back into the sap source tank to get the better of both goals. The book for the Merlin said not to exceed operating pressure of 75 psi, I was using a fairly cheap shallow water pump and it maxed out a 60 psi, to go higher I would need a more expensive pump. I also had a 5 micron filter ahead of the RO that may have killed my pressure some.