Going way over draw temp

[Windy Acres]

So we started boiling concentrate this year on or 2x8, and no matter what I did for adjustments, I just couldn't find a sweet spot where the temp wouldn't rise 3 or 4 degrees in the middle of the draw, we have AOF/AUF and burn all kiln dried hardwood, split to the proper size, we average around 85 gph, full hoods and preheated, and a bubbler, stack temp holds 900-1000. I'm wondering if I need to cut down the auf and not run it so hard with concentrate?

[maple flats]

Does it do that only on the first draw after you reverse flow or all of the time?

[DrTimPerkins]

Where are you placing the temperature probe? Have you tried moving it further back in the pan? Is the last partition noticeably cooler (less rapid boil)? When you switch sides, does the problem change from side-to-side?

With our former evaporator (Leader 3' x 10') boiling 15-17% concentrate, on the first draw of a boil or after switching sides we would have to start drawing off about 2.5 deg F cold, and it would rise about 2.5 deg F over the set temp, and make about 10 gal of syrup in that first draw.

On the new Lapierre Volcano 2000 4' x 12' boiling high concentrate, we start drawing off 3.5-4 deg F early, and it can rise to over 10 deg F above syrup on the first draw. The front (syrup) pan on this rig is 4' x 8', and we're running 2" deep, so there a lot of syrup in there. We end up with about 25 gal in the first drawoff. Can get a little exciting, but with the Riello burner you can adjust the heat anywhere from 20-100%, so we'll dial it back a little until after the first draw is done. Once that is over, as long as you don't change anything else, with the modulating drawoff it just runs almost perfectly smoothly for hours. Switching sides can be equally exciting, but we find we haven't had to switch sides very often these past few years.

[Haynes Forest Products]

I can sympathize with the out of control fright train coming into Union station. On my rig it was to much heat with a too little draw off valve and not knowing that I was drawing off at the coolest part of the finish pans. You mentioned concentrate but what percent because going from 2 to 4% was crazy for me the first time then 4-8% made me do some changing of the rig BUT 22% took some real changes. The problem people get into is they try and do to many changes without really knowing what is the main cause. You want to really feel like burning the shack down is have a bad temperature probe that fluctuates back and forth never settling down to a constant temp. I made my best syrup once I took the time to calibrate ALL my probes and then trusted them. That includes calibrating the PID to the probe.

Once I realized I was making over density syrup in my first channel of the first finish pan nearest the flue pan and then it ran thru the other 3 to the undersized draw off then I made the big change. OH YEA all the time I was running my oil gun on high fire............What a dumb a$$ I was. Just dont make 5 changes all at once because you will never know what was the biggest contributor.

[Bucket Head]

Chuck,

What did you "change" when you had over density in the channel next to the flue pan? Was it just a draw off change or did you change the plumbing so that channel became the last (finish) channel. I have considered doing that with mine since that channel is over/closer to the hottest part of the firebox. The front channel is cooler being on the "outside" so to speak and the repeated door openings to load wood doesn't help either.

[Potters3]

Have had the same issues with spiking temp on draw. Few small changes seemed to have help. We boil 16 - 18%
2 1/2" to 3" deep in the front pan
start drawing a little early, a trickle to get it going, never open draw valve past half way. scoop over sap if needed.
clean the front pan when it starts to act funny

[Haynes Forest Products]

Steve I have become a SS milk house pipeline whore I buy up all the fittings I can find. I have a assortment of all kinds of specialty fittings. I have a Lapiere waterloo small pan set that you can reverse but you have to switch out all the equipment from side to side. What I ended up doing with an assortment of 2" sanitary fittings and elbows is come out of the flue float box and skip past the 2 finish pan plumbing and into what used to be my draw off port. I then put the draw off plumbing on the channel next to the flue pan. That made it run like it should very predictable and steady. I also did away with the bypass plumbing and got my drawoff plumbing short and sweet. Once things settle down I can run it on high fire

[Maple Man 85]

This is a common issue with our rig as well, when we are done for the day we drain the syrup pan (4x6) into our draw tank and clean the pan. From there we pump it back into the pan (this jacks up the gradient) so our 1st draw is like 30 gallons! The first time this occurred I about s#@! cause we were not prepared. But it was really cool to see that much syrup came off at once (we prefer to have the 1st draw come off a bit heavy). I'll put the hydrometer right in the draw tank and pull hot sap from the reverse flow valve to achieve the proper density and then send it through the filter press. That how we get around it (then play with the auto draw temp setting). The thing to remember is that syrup comes off the same way sap enters. Here is what our 1st draw tends to look like...

https://www.facebook.com/northwoodsmaplefarm/videos/607994252868512/

[Windy Acres]

Yes this happens all the time, we are boiling 13-15%

[mellondome]

I boil 18%. When I shut down, i keep one partition of near syrup from the front pan. When I start up i will add this to the draw off box just before the front pan starts to boil. As the next to last section nears syrup ( using a hydrometer) i will start a draw. From there, i will have a constant draw the entire boil from the bypass of my autodraw. The autodraw is set to 2 deg over syrup to keep things from getting out of control. When it is all blended in the drawoff tank, the highs and lows balance out.

[nymapleguy607]

How big is your syrup pan on your 2x8? I have this happen from time to time on my 2x6 with a 2x2 syrup pan. I always blamed it on not being able to get a strong gradient in the smaller pan, and it will start to batch at the center sections of the pan.

[Haynes Forest Products]

NYMaple You said "I always blamed it on not being able to get a strong gradient" I know ill get some flack for asking this but when you say Gradient are you talking about the sugar concentration or the liquid level.

You got me thinking about how I looked at my rig when it was giving me fits because of the highest heat was under my first channel of the first finish pan. I guess my point being was it the density of my syrup causing the syrup to not flow or was it causing the lowest liquid level to be in that area causing syrup to reverse flow away from my draw off. I have corrected it BUT I'm now not sure what I corrected. What Gradient did I compensate for? I believe it was the liquid level differential that I was able to correct with reversing the flow.

[Super Sapper]

Though gradient can be used for sugar concentration or liquid level, it is mostly used for sugar concentration here. My understanding of the gradient in an evaporator is that water if vaporized off and all channels start to lower. Since you are only adding at one end you are diluting what is in that channel as you add sap. As that level in the first channel rises it pushes some of it's liquid at the far end into the next channel to equalize the level. The liquid at the far end of the first channel has a higher concentration of sugar than the incoming sap so the second channel gets to start at a higher level than the first one. As you progress through the channels you get a higher and higher concentration. Even though the level change causes the sap to enter the first channel the sugar concentration difference is what is referred to as gradient.

Now if you want to discuss this over a 30 pack let me know when you are back in Wisconsin and I will see if Joe wants to join in.

[Haynes Forest Products]

I agree with what you said and yet opening the draw off starts another gradient in motion. If all you did was add sap into a channeled batch pan because you dont have a draw off valve then you have a nightmare of the gradient of the first kind.

Now I will be back up in Door County this 4th of July and will gladly meet you guys in Algoma for a few. Plus my sugar shack is always open for some in depth discussions. Heck you never know what I might be willing to part with in the dent and thrown from the truck out of anger pile.

[Russell Lampron]

I draw off heavy on purpose. I have a finisher that I draw off into and when I'm done boiling I correct the density and filter it. It's easier to thin it down than it is to bring it up to density.

I always blamed my small 2x2 syrup pan for not being able to maintain a constant draw and making syrup in batches. I see that you guys are having that problem with larger evaporators too. I increased the depth in my syrup pan from 1" to 1.5" and the batches are bigger with smaller spikes in temperature. I sometimes boil at or near 2" and it's even more consistent. There are times when I can get a draw started and keep it going for more than a half hour.

[SeanD]

This is a common problem for me as well - though I only boil 8%. I have a 2x2 syrup pan with the first channel running the width of the pan then the next four run the length of the pan. The draw off port is away from the arch door back towards the middle of the evaporator.

I end up making syrup in the middle two channels and just try to push/pull it over and out. I used to get worried about it, but now I just live with it. It's part experience, part art, part prayers, trusting the rig and not panicking as the temp rises 2, 3, 4+ degrees over before it peaks and begins a slow drop down again as the heaviest stuff comes around the corner. Of course, I do panic and scoop some sweet from the back to the front. I've learned that when I fire, the cool air coming in drops the boil for a few seconds and the sweet from the back catches up and gives the front pan a push.

I try to fire as far over to the draw side as I can, but it's a two foot pan and there's not too much side to go to. Haynes, you got me thinking about this a little differently. I know the two middle channels are the hottest ones where the syrup is getting made, but I hadn't thought of the draw off channel as being cooler. It's sounds like the same thing but it's not. Thinking more about the draw off channel I realize almost an inch of it's length is sitting on the rail and almost an inch is sitting on the front rail. My draw off channel has maybe 15%? less fire to sit on. I've been focusing my attention on the firing, but it's really a lack of fire or cooling that is my problem.

I have the ability to reverse the flow and draw from the channel that runs the width of the pan, but I can't get it to work. That's a problem I'll post another time.

[Haynes Forest Products]

SeanD I have come to to learn to trust what my fancy smancy guages and probes say. Now it took abouit 5 years of near disasters to get my rig running like a well oiled machine. I reversed my flow and that got the syrup running in the right direction. Then because my new set of finish pans had the temp probe ports in the trailing channels only a was heading over the the rig with a cordless drill with 1/4 bit in hand when I came up with a better solution. I had a friend make up a nice SS clip on temperature probe holder. When you think about it your controlling a valve that is about 12" from the control unit. My probe is 4-6" inside the channel then the draw off box is another 3" on top of the 4-6" piping outside the rig to the valve. Now I understand that YOUR rig might run fine with that but mine runs better when I came up with my probe 100% vertical even slanted slightly into the drawoff box. I get a better reading there.

Now when I boil alone and Im doing all the concentrating, boiling, filtering, transferring, filtering, checking on all the levels, foam pumps things can get hectic. I have float switches and buzzers on everything. My shack sounds like a jumbo jet flying upside down. BUT I get a rhythm going that matches my evaperator and we become one with each other. I control it and it controls me. Once we both settle down and level off at cruising speed we can relax. Now just screw one thing up and the beatutiful music is over and done for about 10 minutes.

Being slow and steady with the changes keeps the rig running at top speed. The things that can throw you off and make the gauges spitter spatter are forgetting to defoam, keep the sap levels on point, forget to fire, bang into a valve and open or close it by accident and the list goes on. Then you decide to change the wrong thing...............what I mean is you decide that scooping sap forward to "HELP" something heck I don't know what but your also depriving some other area of the pan of its sap. next time your walking in a nice orderly line lets say at IKEA and try this just shove the old lady in front of you the one with the Turkey leg half way down her face. Now speed up filling the void in front of you.....get the picture now the guy with the entire kitchen in his cart will run up on you, but your now laying on top of granny doing the Heimlich and now our neat little line is a mess. Once the syrup is traveling thru the channels being pushed along buy the incoming sap that is CONSTANTLY coming in and you draw off is matching it at a slow trickle WALK AWAY.

Now I have a few scoops the screened one and the solid one and I took the 4' handles off and have them in the rafters. I know guys use them for sheeting their syrup to see if its close and that's fine I just don't have much use for them. Now I do remember the time we used them to get a beer cap out of the pan after my idiot buddy dropped it when he reached into the funny looking FOG. Well I was wetting myself with laughter seeing him outside the shack with his arm in a snow bank. What a dumb *** but that's some funny entertainment. Now guys watch the rig I need to go change.

I have learned to just slow it down and quit changing the things that don't need changing.

[mellondome]

For what it is worth, i am running a 2x6 with a 2x2 front pan. Drawoff box is at e back ( grimm /leader ). I run about 1" deep. ( as stated earlier 18%) Once i have the continuous draw going... everything just flows..
You have to be willing to start drawing from the box just before the center gets to syrup. It will go way over syrup for a quart or so then settle down into a nice cotrolled flow. No batching..

[Windy Acres]

Yes, my front pan is 2x2, although it isn't a cross flow, I have a bypass valve that I keep a steady stream about the size of a pencil lead going at all times, maybe I just need to open that a little more-

[nymapleguy607]

NYMaple You said "I always blamed it on not being able to get a strong gradient" I know ill get some flack for asking this but when you say Gradient are you talking about the sugar concentration or the liquid level.

You got me thinking about how I looked at my rig when it was giving me fits because of the highest heat was under my first channel of the first finish pan. I guess my point being was it the density of my syrup causing the syrup to not flow or was it causing the lowest liquid level to be in that area causing syrup to reverse flow away from my draw off. I have corrected it BUT I'm now not sure what I corrected. What Gradient did I compensate for? I believe it was the liquid level differential that I was able to correct with reversing the flow.

When I talk gradient I am referring to the sugar concentration through out the syrup pan. When I have talked with older sugarmakers in my area they have said that a small rig like my 2x6 is harder to make syrup on than a large evaporator. They always said its because you don't get the syrup "pushing" through the evaporator when the gradient develops. I thought that when I added my RO that I would no longer have the syrup drawing in batches, or starting to make syrup in the center partisans of the pan. This never went away, I just make more syrup per hour this way. H20 innovation put out a video of Glen Goodrich's new high brix evaporator and he explains that density gradient doesn't really form in the flue pan, its more to do with the size and linear travel the syrup needs to make in the syrup pan. If you think about a 2x2 syrup pan, most likely there are 4 sections to the pan for a total of 8ft of travel. I believe that truly isn't enough space to work smoothly. From talking and reading what other producers have experienced I think a larger syrup pan with more linear travel will make the evaporator run smoother. I am now debating on having a 2x4 syrup pan made and stretching my arch to 8ft in length, this would give me a linear travel length of 16ft which should help with the flow issues.

[wiam]

When I had a 2x6 boiling around 16% I would get a big draw at first and then could usually run a small pencil sized stream. But I always ran a second thermometer probe where the syrup entered the front pan. This lets you know what is on the way and you can adjust your draw valve to compensate.

[Haynes Forest Products]

Great information and it is enlightening to see that at times I was making the wrong assumptions and working off bad information. Waim I had a dial thermometer in my center pan first channel and I treated it more like a novelty and didn't take the time to calibrate it and use the information. Then as I concentrated higher and saw the dark color in the transfer float box i knew why I was having control problems.

Then when I tried to compensate that is when the real problems started. I started to overcompensate and started a SEE SAW effect I would over draw and then that would lead to over cooking. Then I would do a panic draw off and an emergency shut down followed by a holding down of the float. Now my flue pan has never given me any problems as far as being able to supply enough sweet to the finish pans.

The depth of my finish pan when under a full boil running 18% is a very angry animal. In the area over the transition the sweet is up almost over the dividers cascading down to the area by the flue stack at a depth that just washes over the tops of the flue. At times I can see the tops of the dividers steam dry in a micro second. I have never had what I would call the traditional boil in my flue pan. I have seen pans with a nice even level of sap boiling way all nice and even like a pond during a rain storm.

I hesitate to change it because things work well now but maybe for fun I should run the pan with about 4" sap over the flues and see what happens.

[Super Sapper]

On another site some of the people reduced the size of the opening between channels and reported much more even draws. The claim I think was that there was back mixing between the channels.

[Haynes Forest Products]

That can also be deceiving because you will get nice shinny bubbles in the last channel by the draw off. That is a clear indication that the syrup is getting very close to being over density. When you get the really high bubbly candy looking bubbles they build up and spill backwards making it look like the liquid is moving backwards. I think in reality the syrup below isn't its just the higher bubbles moving to a lower level/depth.

[Windy Acres]

So is the general consensus to try opening my bypass a little more, and continue to fire as usual?

[Haynes Forest Products]

What bypass are we talking about because bypass imply s your going around in stead of using a valve?

[mellondome]

On my drawoff, i have a tee. One side goes to the autodraw, the other to a ball valve( originally incase the drawoff didnt open you could still draw off) this is that i refered to as the bypass valve. It bypasses the autodraw.

[Haynes Forest Products]

OK that is what were talking about BUT what is Windy Acres bypassing. If its an auto draw off I'm confused. Now if he is relying on the auto draw to open during big dumps but bypassing it to have a continuous flow is weird.

[Super Sapper]

There should be a ball valve just before or after the auto draw valve. This is used to adjust the flow when the automatic valve opens. The auto valve opens fully and you do not want a full flow coming out of the pan. If you are surging too much close the throttling valve a little or open some if it is not going fast enough. On the first draw you may need to have it open a tad more but then adjust it after that to maintain as consistent a flow as you can.

[Haynes Forest Products]

I have a throttling valve on mine also. I also noticed that with the modulating style valve people are getting away from the throttling valve. I have had about 5 different derivations of the same set up. I found my best system is to have the throttling valve after the auto draw valve so it stays cleaner from sugar sand and flakes. I also eliminated as much horizontal fittings so crap cant settle impeding the flow.

We agree that a throttling valve isn't a bypass valve.

[mellondome]

OK that is what were talking about BUT what is Windy Acres bypassing. If its an auto draw off I'm confused. Now if he is relying on the auto draw to open during big dumps but bypassing it to have a continuous flow is weird.This is how i do it. I run a continuous draw from the bypass valve. The autodraw is set to 2 deg over.
The problem you have if you are putting a throttling valve on your auto draw is that if for some reason you get a large draw ( because now you are batch drawing) you run the risk of burnt pans because you cannot draw off fast enough. This is especially true if you are using it to create a continuous draw through the autodraw.

[mellondome]

When i first put am auto draw on my pans, i was using wood for fuel. It was a lot high temp fluctuations when the valve opened to draw. Starting @ the temp i set it to and going 7 or 8 deg over. So i then set it up with a valve in line with the auto draw so it was more of a continuous draw. Problem is you get a big draw and you start making smoke in the pans because you have limited your draw speed. This lead me to putting in the bypass valve and using it for the continuous draw and the auto draw for "slugs" of syrup the continuous cant accommodate.

Now, i no longer use wood. With natural gas burners the heat is consistant and the syrup flow is very predictable. BUT.. i still occasionally get the slug of syrup that opens the autodraw. No more smoke in the pans . I also have moved my temp probe from the factory location (front of final run) to just inside the pan at the draw off box.

[Haynes Forest Products]

Mallondome I also shave my head....................:lol: I now understand your set up and why. With oil I have had to go to low fire and that slowed it down but in reality it sped up MY process. I also agree that what works for you is the best method. I get sidetracked to easily and one time when I was doing the trickle method before my auto drawoff I walked away and over flowed my tank and ran everything on the floor. Every time I put into place an automatic system I pass the responsibility farther down the line and it bites me in the butt.:(

[Windy Acres]

yes, after my throttling valve, and before the auto draw, i hate a T, one side is the auto-draw, the other side has another valve, which i leave a small stream running out of

[Windy Acres]

18696 it's not the best picture , I had to crop it out of another one

[Windy Acres]

18697 that's the picture it came from, and the rest of the crew!

[Haynes Forest Products]

So you use the auto draw as a safety valve. Got it and its not a WRONG way just a different way. Do you find that sugar sand and chips don't settle in the auto valve pipe and cause a clog. I had that issue when I had that style plumbing?

[Windy Acres]

I've never had a problem, but I push everything out of my front pan with permeate every time I boil, I believe that helps alot, I only leave the other valve open a little more than a fast drip, I'm thinking I need to run a bigger stream, and maybe that will keep the front pan moving a little more to avoid the overtemp