recirculating sap

[sapman]

What flow rates do you who recirc. try to achieve? I started recirc. today for the first time. I assume you run the permeate less than the concentrate, to keep the high pressure off the membrane? And if doing a rinse every few hours, how long do you rinse for? Any warm water washing involved?

Thanks,
Tim

[Thompson's Tree Farm]

Tim,
I try to run permeate and concentrate at about = levels. Main thing is to make sure there is plenty of water going over the hill as much as possible. I try to do a rinse every 4 hours. If there is time, I run the full 650 gallons through, if I'm backed up, I'll run 200 through and start over. About every 3rd time, I like to do a full wash. For a real pro's opinion, check with 802maple.
Doug

[Russell Lampron]

Tim I set my flow rates so that they are equal and at 250psi. If the concentrate flow needs to be higher to get more permeate flow I adjust it so that I get the higher permeate flow.

When it is time for a rinse I switch over to permeate and concentrate until I have all of the sweet flushed out of the membrane. Then I switch my settings to wash and run about 100 gallons of permeate through it. I have 1 4" membrane. If you have more membranes or a larger one you will need to run more permeate through before you go back to concentrating.

I do a soap wash after every use regardless of hours used.

[maplwrks]

I keep my concentrate flow up around 4gpm or so, and the permeate side on 9 gpm. This removes 630 gallons of water an hour. You will get the feel of the sweetness of the concentrate by watching you pressure guages. When mine climbs over 400 psi, I know it's time to throw it in the evaporator.

As far as hot water rinsing, I rinse religiously every 4 hours, or soone if I'm starting to run high pressures.

[Brian Ryther]

Mike,
Is that hot water rinse with or with out soap.

[maplwrks]

Without soap---I put soap in every 12 hours

[sapman]

Mike, do you preheat the water with an element, or let it run a long time to heat up itself? How long do you wash it, or does it just shutdown on high temp?

Thanks guys!
Tim

[maplwrks]

I have an element that heats the water. I heat it to about 90 degrees and let the machine take it to high temp. This takes about 3 hours. For those of you that are running Springtechs or Airblo ROs, they heat the water very fast by themselves. I would let them go to high temp and then rinsewith permeate. If I'm backed up with sap, I'll do a quick hot water rinse for 20 mins. and rinse for 10 mins. This gets a lot of the crap off the membranes, and allows me to keep rockin'.

[sapman]

Mike, when you do the soap wash, do you check the water with a ph meter and just add the amount necessary to get the ph right? Or do you just follow label directions?

[maplwrks]

I check it for pH---For my membranes a pH of 11 is recommended. I mix in my soap to the correct pH, run the wash for 10 minutes and recheck. I add more soap if necessary to get it back to 11.

[doocat]

Mike,

On my Airablo 600 gpm machine if I run 4 gpm on the concentrate the permeate usually runs about 5 gpm. Is your machine adjustable on the permeate side or is my membrane just not as efficient?
As the conentrate gets higher the permeate side appears to drop. At some point we have 2-3 gpm on concentrate and 3-4 on the permeate. Any thoughts or fixes. Is this just a slower machine.

Craig

[maplwrks]

Craig--As you recirc. you will see a drop in the permeate. I almost always have the permeate finish up at a lower level than my concentrate. Just keep doing what you're doing, remember, you're just trying to remove water!

[markcasper]

I am disgusted that I went to DA in Monday nights 2nd boil of the year. I fired last Saturday for the first time, recirculated for about 4-5 hours into 1000 gallon RO feed tank and kept adding raw sap to the tank as the RO removed water.
on the first boil I was making light and high medium out of all the sap that had been stock piled since the previous Monday.

I basically did everything the same both times and the sap was very clear and good looking. The only thing different is I did not wash the 1000 gallon RO feed tank from the previous run which I had recirculated into. Could that be why it darkened up so much? Does anybody have any research as to how high or long you can go and still get away without grade change.

Now we lost most of our snow and the chances of getting back to light are pretty well shot and I have only boiled twice. I am going to quit recirculating if thats the case and just run it through once but start the RO earlier in the session so I have something to boil even if the concentrate sits for 6-8 hours.

[sapman]

Mark, I definitely noticed darkening in my syrup when I started recircing a couple years ago. When I single passed to only about 8-10%, I never made so much light. I'm starting to do that again, sort of. With the new membrane, I can single pass to almost 13% from 1.5% sap, though it takes time.

You do need to keep the tank clean, cause of all that sweet concentrate.

[802maple]

I think if you guys are seeing darkening due to recircing, you are doing it to long. I only do a tank of sap to 4 to 6 percent and then immediately start feeding the evaporator and I make mostly light syrup or medium amber at the darkest with sap at this stage of the season. As quick as the feed tank to the evaporator is wet on the bottom, I fire the evaporator. Last night we started boiling when we had less than 5 gallons of concentrate in the tank and 2 hours later when the RO ran out of sap we only had 10 gallons in it and shut the evaporator down. I do it this way with wood or oil and as long as I can run the RO for an hour or more I concentrate and boil every day. If I can't run the RO for an hour I boil in whatever sap is in the sap tank anyway, I don't care if it is only 50 gallons. If sap runs into the tank that day it will be boiled that day, that is key to making lighter syrup, not cost effective to some, but to a bulk producer it is a must to keep that syrup as light as possible. I know some will say that by heating it up that it will darken, but not as much as it will by leaving it in a tank for bacteria to grow.

[Bucket Head]

I have a question about the heating/washing times that were mentioned. How long are the washing times on other brands compared to the Airablo/Springtech machines that "heat up quicker"? What is a typical wash time for an Airablo unit? Why are they quicker? I'm guessing they have much larger heater elements in them?

I'm new to RO technology and I'm trying to find out as much as I can about the unit I have. Thanks for allowing me to somewhat hi-jack this thread.

Steve

[maplwrks]

Your Airablo RO uses the high pressure pump to wash, where a Lapierre and a CDL use only the feed pump to wash. Running the high pressure pump heats the water very fast. My Lapierre wil run for 6 hours or so before it shuts off on high temp.

[Amber Gold]

Jerry, are you recirc'ing to 4-6% while removing half the water, then do you adjust your conc./perm. flow rates so that it'll take it to 10%+ in the next pass?

And is it 4-6% tank sugar content or what's coming out of the conc. flow meter?

If you're only running the RO for an hour or more, how are do you get enough perm. water to wash and rinse the membranes?

[802maple]

I recirc until the tank is 4 to 6% then I set the RO to feed the evaporator at the exact same feed rate or a little higher that the evaporator will boil away the sap. This will usually be in the16 to 18 percent range coming out of the RO. If I take the tank to 8% I am usually feeding the evaporator 20 % percent or better.

As far as running the RO for an hour, you will produce enough permeate to do a rinse large enough to push the wash water out. I do not have to do this many times a year and as you know I do promote large volumes of rinse water, but ocassionally I have to bend the rules. If you have a 600 machine in a hour you will make atleast 450 gallons of permeate which is more than a lot of companies recommend to rinse it. I use 35 gallons of it to wash and the rest to rinse. I doesn't make any difference which size machine you have, a hour will make enough to wash and rinse once in a while.

[doocat]

So 802 when you start to feed the evaporator do you crunch the concentrate down to 2 or so to get the sugar up from 4 to 16 instead of letting it just keep running at high flow for a longer time? We run a Airblo 600 with two membranes. We are not having a problem with grade but just curious.

Thanks, Craig

[Bucket Head]

Mike,

Wow, six hours for a wash. I did not realize a wash took so long. Does your machine not have a heating element? Do you have an idea on how long an Airablo machine will run on a wash cycle? I know mine has a heating element. What are the positives and negatives between a long wash time with just the feed pump and a shorter wash with both pumps running?

Thanks,
Steve

[802maple]

So 802 when you start to feed the evaporator do you crunch the concentrate down to 2 or so to get the sugar up from 4 to 16 instead of letting it just keep running at high flow for a longer time? We run a Airblo 600 with two membranes. We are not having a problem with grade but just curious.

Thanks, Craig

Usually I am closer to the 6% and the evaporator that I boil on requires 3 gallons a minute to keep up ,so that is where I set it

[Brian Ryther]

My question is what happens when you loosen up the ro and for a day feed the evap 6% then shut down. The next time you boil you feed the evap 12%. Do you run the risk of having an inverted gradient in the evap and make syrup three dividers back from the draw off?

[802maple]

I have gone from 6% to 24% and back again and never had any problems. Of course I use superior equipment with crossflow flow pans so that might answer why. LOL

Seriously, I haven't had problems with that with either type of evaporator even those pesky reverse flows. If you don't pay attention to it I suppose you could, but if it is getting close to that work it around so that it doesn't occur.

[sapman]

If I recirc my RO for only an hour (600 machine, but in reality less), I don't know if it will have the sap up to 6% already. And I need about 2 gpm for my evaporator, so putting it right up to the feed tank will probably only give me about 8-10% sap. I'm used to 13-14% (love the oil savings). I definitely see what you're saying, though, and will see if it can work for me.

[sapman]

And about using up small amounts of sap, running from the bulk tank to the feed tank requires going through the RO. I don't think there is a way to bypass the membrane on my machine, so I can just get the raw sap into the feed tank.

[maplwrks]

Steve--If I don't use the heating element, it will take about 6 hours to wash. I can cut that time down if I preheat the water to 85 degrees. My limited experience with an Airablo 600 was that it heated the water very fast---1 hour. A long slow wash is really what you want to remove all of the impurities from the membrane surface.

[802maple]

Tim, you are right when all you have is the RO to move your sap. In my setups I have a regular pump also in the RO feed line to move sap to the feed tank.

[Amber Gold]

Jerry, when you start sending it up to the feed tank, what pressures do you recommend? I recirc at 250 psi, but had to crank it up to 380 psi to get 50gph conc. and 80gph perm. flow rates.

[markcasper]

MAYDAY..........Another screw up last night. After washing the RO I immediately went to flush with permeate as the temp outside was 10 or below. I was bottling syrup and just as the permeate was about to run out I noticed the washing valve was in the open position. In other words there was permeate going down the drain, as well as into the feed pump - membrane at the same time. I only had about 400 gallons of permeate total because I only gathered 700 gallons before the big freeze. Question?? How much permeate went down the drain and how much went through the machine? and was it enough for a flush? The rinse permeate was dumping into the wash tank as it always does from the tower.

(The flush session was at least 30-35 minutes before running out.)
On a side note and I learned something new. When I put the cleaning filter in the rubber o-ring fell on the floor. It must have had a piece of grit in it because it was leaking slightly during the flush. I tried to loosen the blue cartridge while it was running and pulled my back out as it wouldn't budge. So I shut it off and the filter cartridge turned with ease. My observation, there is a heck of a suction if that alone kept me from removing it while it was running. That is why I am thinking not too much permeate went down the drain even with the wash valve open to drain.

[maplwrks]

To be safe--The next time you have sap, concentrate some sap and throw away the concentrate and permeate for a short time and then start saving the permeate. This would be similar to what you would do at the first start up of the year. Keep enough permeate to give it a rinse and go back at it. I know, it sounds like a waste of sap, but the consequenses down the road wouldn't be good if you had soap in your syrup. I am not a proponent of using tap water to do this, but if you use it to flush out your membrane at the start of the season, then go with that.

[sapman]

I did this just last week when I ran lower than I realized on permeate to rinse with. I actually left everything in the rinse position for the first bit before concentrating.

[Brent]

Steve
the cycle does not need to take that long (6 hours ). The literature I got from DOW shows two key things. pH and temperature. 95% of the cleaning is done after the temps pass the 100 deg mark and the pH is higher than 10. And the effectiveness curve goes nearly straight up between 10 and 11.

So do whatever you want to raise the temps quickly, but not suddenly like filling the wash basin with hot water ... add it gradually and keep checking the pH. As the soap does it's cleaning, the pH is likely to drift down some, so you should keep testing it to keep it at 11.

See the links at the bottom of this page
http://www.duffyslanemaple.ca/syrup-equipment/syrup-equip.html

[802maple]

Jerry, when you start sending it up to the feed tank, what pressures do you recommend? I recirc at 250 psi, but had to crank it up to 380 psi to get 50gph conc. and 80gph perm. flow rates.
Usually between 350 and 400, so you are right there.

[Bucket Head]

Thanks guys. I appreciate the responses. Soaps, washes, wash times, heating, PH levels, high temps.- its all new to me! I'm sure I'll have more questions as I continue to learn about RO operation.

Steve

[danno]

Has anybody found a reliable/accurate ph tester? I have the stips - 1-14 scale. It seems that no matter how much soap I put in, I get a reading of 12, so I don't trust the strips. Although I have heard of some soaps have a max ph regardless of the amount of water mixed with.

Or let's try this - how much soap do you use with 20 gallons of water? I'm using the dry alkaline soap that comes in the small white bucket. I've been mixing about 2.5 oz. with 20 gallons of water and ofcourse getting a reading of 12;)

[802maple]

I found that with the new strips I have bought this year that they do the same thing, I was very pleased with the ones I have used in the past but not these.

[Russell Lampron]

I have an electronic ph tester. It is the same one as in the Bascom's catalog. You can probably find one on ebay.

[Brent]

I did a fair amount of checking into testers this spring and came to the conclusion that strips are not accurate enough.

Many have had problems with electronic testers but most of them are cheap models, costing $25 or so.

When you get up to the $ 100 to 150 price range you get testers that you can replace the probes and they offer calibration solutions at 7 and 4 pH, as well as storage solutions. So I ended up selecting a Hanna 98130 at $130. Got 4 and 7 calibration solutions, a storage solution, a cleaning solution and a space probe all for
$ 220. I should be set for a least 1 year and the solution bottles should last longer.

I'm going to be shooting for a hot wash at 11pH and I don't want to screw up my membranes by going over that in the middle of the season, wasting several days of poor performance before I figure out that I really have screwed them up.

Same old same old. You get what you pay for with very few exceptions.

For what it's worth I ordered mine through www.eseasongear.com (http://www.eseasongear.com)

PS this one will also do TDS tests which will confirm how clear the permeate is and this will give you a pretty good idea if you're
passing sugars, without doing a boil down test.

[802maple]

I never have had a problem with the strips until this year as I guess Lapierre got a new brand.(probably cheaper, a good way to sell ph meters) My membranes have always when tested been better then what they are rated for and don't pass sugar.

[sapman]

Jerry, back to recircing for an hour. What % are you feeding your evaporator with, doing it this way?

Thanks

[802maple]

You may have misunderstood me,if I have only enough sap to concentrate for an hour. I send it directly to the feed tank as sweet as i can get it.

[sapman]

Sorry, what I meant was, if I understand correctly, is that you start out recircing for an hour, then start feeding the evaporator at 3 gpm, right? Just wondered what kind of sugar % you will then be boiling?

Thanks

[802maple]

Tim, what I usually do is bring the tank of sap by recirculating to near the 6 percent area, I like to boil atleast a hour, so if taking it to 6 percent will make it so I can't boil for an hour, I will take it to something less if I recirc at all and then start feeding the evaporator. When the tank is at 6 % it is quite easy to take it to 16 with our setup and keep up with the evaporator.

[sapman]

Wish my RO was capable of flow rates and pressures like yours is. Don't think 6-16% in one pass is possible on it.

Thanks for the explanation!

[802maple]

Ours isn't capable of 16% percent in one pass either, it is only capable of that after the tank is up to 6 percent after the recirculation process. I think you are still misunderstanding me and that is a problem everybody has with my feeble mind. LOL

This is my process, less than 500 gallons I boil it into the evaporator as rawsap, 600 to 1000 gallons, I run the RO straight into the evaporator as sweet as I can get it, usually about 8% and finally anything over 1000 gallons I recirc until the tank is 6% and then to the evaporator at about 16%. When I go into super concentrate mode, I take the tank to 12% and then give it to the evaporator at 22 to 24 % sap. I don't do this very often with the 600 machine that we use, only when the sap is very cold so that it will last longer. I did it all the time when i used the 1800 gallon machine of the past.

[sapman]

Got it! I assume the membrane always cleans up good after going into the 20s with a soap wash?

Thanks again.

[802maple]

Yes they do as long as I use my usual rinse and wash schedule and don't let the membranes get fouled to begin with.
The wood chopper that keeps his axe sharp will have a bigger pile of wood at the end of the day then the one who lets it get dull before sharpening. lol