recirculating to raw sap tank

[Ryan Mahar]

Hello all! This year I will be recirculation my first pass into my raw tank until it is a little higher concentration before I process to my concentrate tank. Looking for about 12-15% before it hits the evaporator. My question is , as the first pass goes back into the raw tank, I expect it will sink to the bottom. Is there any trick out there to better distribute the first pass with the raw sap so that it mixes better?

Thank you..............

[eagle lake sugar]

I recirculated like that for the past two seasons. I ran the line from the r/o to the back of the sap tank opposite the outlet and occasionally stirred it. I'm taking a different approach this year, I bought a concentrate tank. What I found was that when I got home from work and was ready to start boiling, sap was still running in. As you're running it through the r/o and sending it to the evaporator, the sap in the tank is getting diluted with the new sap. By the time the tank is empty, your r/o is basically processing raw sap. This year I'm going to bring it up to around 6% into the concentrate tank, do a quick membrane wash, and squeeze it to 14% to 16% when I send it over to the evaporator.

[maple flats]

Just run it to your head tank, and then recirculate it back to the RO and back again to the head tank. Then when you get to the 15%, just switch to draw from raw sap again. That is how I do it. I'm plumbed so the only switch I need to make, is to close one valve while I open another at the same time.

[madmapler]

I did it that way last year and will be doing it again this year. I used a round poly tank and had the return line running in so as to create a current around the tank like a whirlpool. I stirred it occasionally as well. When I sent it up to my head tank the sugar seemed to stay consistent from start to finish. Its not the ultimate method but its sufficient.

[Tmeeeh]

We set the RO so the permeate flow and the concentrate flow are the same rate(gallons per minute). The concentrate goes back into the raw sap tank until the concentrate coming out of the RO machine is 4 to 5 percent sugar. We drop a small submersible pump into the sap tank to keep the sap in there stirred up. Then we tighten up the RO machine a little so the concentrate is coming out at 13% and send that to the head tank to feed the evaporator. Very soon after we start sending the concentrated sap to the head tank we start boiling and continur until the RO runs out of sap. Some raw sap is often still running into the raw sap tank diluting the partially concentrated sap in there. We watch the concentrate and tighten up the RO machine a little more to maintain around 13% going to the feed tank.

[Ryan Mahar]

Great replies everyone ! Thank you ! Now if we just get some warmup in temps so we can fire up the arches we'll all be happy!!

[unc23win]

I did it that way last year and will be doing it again this year. I used a round poly tank and had the return line running in so as to create a current around the tank like a whirlpool. I stirred it occasionally as well. When I sent it up to my head tank the sugar seemed to stay consistent from start to finish. Its not the ultimate method but its sufficient.

That is an interesting idea Sean. This will be my first year attempting to recirculate depending on the amount of sap I might not have any other choice other than back into the raw tank, but I am hoping to do some plumbing for other options. It is one of the hundreds of things I think about on daily basis in this pre season preparation.

[wiam]

I have an 1.25" bulkhead fitting in the bottom of raw tank. When recirculating I put a piece of 1" poly into this that comes over the top of the tank. There are holes cut in the 1" at the half tank level. The RO would recirculate and shut down. Then I would pull poly out. Rinse and run it to feed tank.

[doocat]

We have tried both recirculating to the collection tank and then to a "concentrate" tank. We have found that two passing, once to a concentrate tank and then second from there to the head tank seems to be a better approach for us. With raw sap continually coming in we end up with too much partially concentrated sap in the main tank so it will get left overnight unless we boil all night! (getting too tired for that). We sat in at a seminar at leader a couple years ago and the speaker seemed to promote the two pass process as faster and more efficient. Just my two cents.

Our next investment is a three post RO to eliminate the process totally. Someday.....

Craig

[ennismaple]

We've been recirculating the past few years and as long as the RO is dumping 50% to 60% of the sap as permeate on every pass it doesn't matter what tank the concentrate it sent to, IMO. We had several days last year where our 3000 gallon raw sap tank was full when we started the RO at 6:00 a.m. We recirculated for 4 hours, dumping 300 gallons of permeate per hour, did a quick rinse of the membrane, started sending sap to the evaporator feed tank and fired up The Beast. Yes, as new sap came in the concentrated sap in the 3000 gal tank did get a bit diluted but we were still boiling concentrate at a higher % than if we'd done a single pass only. Some days when the sap is coming in faster than we can process it the only way to deal with it is get a fire roaring!

I agree that if you want to boil the minimum amount of time and use the least amount of fuel you want to get all your sap processed into high test concentrate before firing up but that isn't always feasible, depending on what's going on in the woods and the time you have available to boil.

Now that we've added a 2nd membrane this year our procedure will probably have to change because the RO won't be able to push out concentrate at the same rate as the evaporator can boil it. I am looking forward to boiling half as long!!!

[madmapler]

I should add that all my sap gets hauled in so dilution isn't an issue for me.

[Ryan Mahar]

This seems to be the most efficient and simplest way to do it. It is how I plan to try it at first. Thanks again for the feedback! This forum is worth it's weight in gold for sure! Good luck to everyone this year! -25 below tomorrow!! No sap flow in Vermont yet!