Air injector (bubbler)

[crossroads maples]

I have been thinking of building a injector for our 3x3 crossflow finish pan. Can anyone tell me what size tubing is required to build an injector? What size holes are needed and how close together? How many pounds of pressure do these work best at? How do you supply air to them?

[maple flats]

As I understand them, the air comes from a blower. The air in must be very clean, should be filtered very well. The unit I saw last year or the year before at the NYS winter maple conference was all SS, each tube was just shorter than the pan or flue section it was designed to fit and was about 1/4" in diam with small holes drilled along the bottom of the tube and the dead end of each tube was sealed shut. The flue pan bubbler was all 1 unit and the front pan bubbler was another unit but both units were hooked to the same blower. The tubes were barely off the bottom of each section and every flue section and front pan section had one tube in it. In use the fan blows clean air into the section keeping the bottom of the pan cleaner and reportedly helps make more lighter grades of syrup by keeping niter in suspension and not giving it a chance to settle out and cook to the bottom.
I have plans to make one but not this year. I was going to check into the SS and weigh that against trying copper tube.

[Bucket Head]

You guy's might want to hold off on the bubler's.

They do keep the pan's cleaner, but they also lighten up syrup that would normally be Gr. B or C into somthing that passes for Gr. A.

I have tasted syrup from a bubler that was graded A-Dark, and it was not Gr. A anything!

One of the speaker's at this year's VVS Conference made mention that Canada was contemplating making them illegal. They alter the color of the syrup, which falsifies the grading.

I do not know where this issue stand's at the moment, but it is somthing you should be aware of.

Steve

[Breezy Lane Sugarworks]

I do agree with you that it keeps the niter suspended better, and lightens the color of the syrup. But when the syrup gets graded, at least in VT anyway, you are supposed to be grading by the color AND the flavor, so even though it looks like medium amber but tastes like grade B, It needs to be labeled as Grade B.

[maplecrest]

air injection is for bulk producers at a large scale, if you plan on selling your product locally and are a small producer as ryan stated you will be selling a light color with a different flavor. i went to the air injection study results from to proctor research center. light color every boil but the last. standard evap made b, air made fancy, when i asked about flavor that was not adressed just color. when showed the difference in niter in pans standard dark with niter, air were very clean. so big difference in boiling time in pans and need to change to clean.the flavor issue depends on who you talk to. glenn goodrich has had good luck with it as says he make syrup like he used to with buckets and horses and uses less defoamer. proctor saw no difference in defoamer use

[maple flats]

Doesn't that figure. It seems like everything that appears good is bad for you. I should have guessed. I will look at what is determined on this topic (I usually am so far behind on my plans that this delay would likely have happened any way.
Dave

[royalmaple]

There's a good reason for new grading standards. Should be leaning more towards flavor than color.

When I sold some commercial last year, guy tasted it and said wow, great flavor but boy you got screwed on color. He had no problem paying me for commercial.

If you are selling in drums, you are getting paid more for color. So it would be in your best interest to make the lightest stuff you can. I'd just hate to pass some sub par syrup off as grade A in jugs retail, when it tastes horrible. But boy isn't it light.....who cares.

I was thinking of making a bubbler this year maybe just for the flue pan, I'd like to say in the mid range A grades as long as I can. Personally I think it would help the niter especially from the amount of red maples I tap. But also the RO is going to be a huge help this year. Nothing under 5% sap is going in the rig.

For ease in fabricating I was leaning towards 1/4 copper pipe and fittings then into PVC after the heat.

[maplecrest]

at the maple school there was talk of a new grading system. but there are so many different systems in every state. then the canadian system of aa, a, b, c and d. there was talk of two grades light and dark. or fancy and med as one , dark and b as the other. then comm. but that could be 5 years or more out.and the canadian fed would have the final say if they would change. but states like ohio have no gradeing laws

[Haynes Forest Products]

So I finish up a plumbing job and Im cleaning out the storage and I decide all this copper pipe and fittings need a home. Just some questions from others that have them and what they think.
Im going to use 1/2 copper in the flues into 3/4 manifold in each section and then tie them all together into 1" .
1) Do bubbles carrie more moisture from boiling sap or hot sap?
2) Do you need to have a bubbler in each drop flue or will every other one work
3) What size holes
4) pointing up down sides
5) what size
6) Spacing
7) how far off the bottom do you space them and why?

[WF MASON]

You'd want a tube in every flue, 1/8" hole every 1/2" facing down, with 1/2" legs to keep it off the bottom of the pan. And pleanty of air to power it.

[Bucket Head]

I know in an earlier reply to this post I voted against a bubbler. However, I have recently changed my mind..., sort of.

I am thinking of building a bubbler, but just for the flue pan, to cause an artificial boil in the pan where the boil is not that vigorous. Mainly towards the rear of the pan.

I will not use one in the syrup pan, because it will alter the grade, and taste of the syrup.

Steve

[WESTVIRGINIAMAPLER]

I am curious why you state it will not alter taste by not using one in the syrup pan and using one in the flue pan????

[Bucket Head]

Brandon,

"I" am not stating that, I'm just repeating what was said at a VVS Maple Seminar a couple of years ago.

Syrup is colored and flavored by the amount, or length of time that is heated. Its called the Maillard Browning effect. The bubbler in the front pan speeds up the boil process a little bit, and cools the liquid in the front pan a little bit. That alters the color and taste. At the time, Canada was considering banning the bubblers because of that. Thats why I won't use one in my front pan.

I want to use one in the rear pan to create an artificial boil in the part of my flue pan that does not boil very hard, towards the rear. It will not have an effect, or very little effect, on the syrup there. Your concentration of sugar in the flue pan is no where near what it is up front. So the M. Browning effect is not taking place there like in the syrup pan.

Steve

[Beweller]

Bucket,

Blowing air into your pan will not increase the evaporation rate. It will reduce it.

[MERIDIAN MAPLES]

I've had air injection in my evaporater for 2 years now, and my evaporation rate went up with the injection. We too thought it would lower the rate, but ours went up. As far as flavor goes, we enter our syrup in the Wisconsin Maple Syrup Producers contest every year and get blue ribbons. We have bubbler tubes in every pan, even the finish pan, right by the draw-off. Yes you do make lighter syrup, and with lighter syrup you don't get the stronger maple flavor as you do from darker syrup. I have customers that by my syrup to make sugar and they love the lighter syrup. You will make some darker syrup towards the end of the season, but I haven't made crude oil like I had before the bubbler. Personally I wouldn't be without it in my evaporater now.

[802maple]

I've had air injection in my evaporater for 2 years now, and my evaporation rate went up with the injection. We too thought it would lower the rate, but ours went up. As far as flavor goes, we enter our syrup in the Wisconsin Maple Syrup Producers contest every year and get blue ribbons. We have bubbler tubes in every pan, even the finish pan, right by the draw-off. Yes you do make lighter syrup, and with lighter syrup you don't get the stronger maple flavor as you do from darker syrup. I have customers that by my syrup to make sugar and they love the lighter syrup. You will make some darker syrup towards the end of the season, but I haven't made crude oil like I had before the bubbler. Personally I wouldn't be without it in my evaporater now.

I agree, a local sugarmaker won best of show overall over all grades with his high RO concentrated, bubbler injected evaporator, grade a medium amber syrup here in Vermont last year. I have also witnessed the increase in evaporation. Take the bubbler out of a steamaway or piggyback and see how that works for you.
If any flavor is injected into the syrup it will be because of the source of the air

[Beweller]

Take a look at the Procter results. Air injection increased the heat requirement by about 15 percent. No matter what you do, it is going to take about 1000 BTU to evaporate one pound of water. If you add air injection, you have also to heat the air. Hence less evaporation for the same firing rate.

The Piggyback/Steamaway work because the air depresses the evaporation temperture below the condensation temperature of steam, allowing recovery of some of the latent heat.

Note also that air injection will destroy the effectiveness of Piggyback/Steamaway and of sap preheaters. The injected air at Proctor looks to reduce the dew point to about 150 F.

[Bucket Head]

A bubbler will help the evaporation rate only if you have a lack of "natural" boiling. It will create an artificial boil.

What are all those bubbles filled with? Steam. Which used to be liquid.

If your getting a good boil throughout your pan now, you don't really need a bubbler.

I should have been clearer on the taste changing part of this thread. Jerry is right, the bubbler does not change the taste of the syrup. What it does is it changes the grade (gets lighter) and therefore what grade your eye see's and what grade your tongue tastes are two different things. Thats the "change". I'll give an example.

A couple of years ago at the VVS Maple Seminar (maybe some other Trader's attended this also?) I sat in on a grading and tasting class. It was conducted by Prof. Chabot of Cornell Univ. All the samples were from producers in central NY. At the end, everyone discussed their thoughts on the grades and flavors.

The most distasteful sample was labled Grade A Dark by its producer. Everyone agreed it was not Grade A. It was not even Grade B in taste. It was awful. That syrup was made with a bubler. What it did was it "lightened up" grade C syrup to a grade A color. That is why, at the time, Canada was considering outlawing them. It altered the color grade.

I am not saying a bubbler would alter all syrup. I too know of producers with them that make excellent syrup.

I would'nt use one in the syrup pan becuase of the potential to falsify the color grading. I do want to use one in the rear pan to help create more bubbles, which will help out my evaporation rate. It won't be a huge difference in rate, but every little bit helps.

Steve

[Haynes Forest Products]

Beweller: what your saying is you need more BTUs to make up for the lower sap temp due to cooler air. BUT the dry air that is injected will carrie moist air out of the boiling sap increasing the boil/steam rate increasing evaporation rate. and if thats equal they byproduct is lighter syrup isnt that a good thing. So its all about the lighter syrup= higher payout.........................YEA/NAY

[maplwrks]

The air in a Steamaway bubbles the sap up onto the steam pipes--Bubbling sap with air is just that. BUBBLING SAP WITH AIR!!! Granted, the boiling point of the liquid is lowered with air, but it is still above the boiling point of water. Air injection does not change the efficiencies of any preheater either!! The biggest problem with air injection is usually the fool that installs it to close to his exhaust stack for his evaporator and draws foul air into his system.

[802maple]

I will guarantee you that the air once it reaches the boiling sap is just as hot as the sap it is in if not hotter, due to going thru steam and then hot sap. If sap which (which sap transfers heat slower than air) goes thru a preheater and warms up to 200 degrees, I am sure it will get just as hot in a 3/8ths tube. No matter whatever study that Proctor has done I will argue this one for along time as I have seen my neighbors 3x12 Leader Inferno go from slightly over 150 gallons an hour to just under 190 to 200 with the addition of a bubbler.

I have without a bubbler made the lightest colored buddy syrup imaginable, it was many shades lighter then fancy until you put it on your tongue you would of thought it was fancy. You just have to remember to grade it as it tastes and not as it looks.

[MERIDIAN MAPLES]

I agree with you 100% 802. My evaporation rate has increased from 170 gallons an hour to 190-195 with having the bubbler. Also one must look at ones whole system of making syrup from the trees to the filtering. There are many factors involved to get the end product. I'll keep my bubbler because of how much cleaner my pans stay and the increase of evaporation. I sell my syrup bulk and retail, and I've not had any complaints about flavor.

[Beweller]

Haynes,

The air dilutes the water vapor, reducing its partial pressure. Therefore the water can evaporate at a lower temperature. For the Proctor trials, that was, if my memory serves, somewhere above 200F but definately below 212F.

The lower temperature of the liquid reduces the sensible heat needed to bring the sap up to operating temperature. Evaporation at the lower temperature actually causes the latent heat to increase. Finally, the air must be heated to the operting temperature.

Again if my memory holds, The Proctor test showed an overall result of a 15 percent increase in heat requirement.

Boiling is a process that occurs when the vapor pressure of the liquid exceeds the total pressure. Very small temperature elevations -- and vapor pressure elevations-- are needed to transfer molecules from the liquid to the pure vapor.

Evaporation below the boiling point occures when the vapor pressure of the liquid exceeds the partial pressure of the vapor species. This is a mass transfer process that is dependent on the absolute difference between the vapor and partial pressures and on "mass transfer coefficient". The mass transfer coefficient depends mostly on the relative motion between the diluting gas and the liquid.

The Steamaway and Piggyback work by evaporating into an air stream at a temperture below the boiling point. As long as the heat exchange surface is immersed in pure steam, the steam will condense at the water boiling point,
above the temperature of the evaporating liquid, permitting the transfer of heat and subsequent evaporation (not boiling).

If you bubble air into your evporator, you will no longer have pure steam. As a result, it will only condense at a temperture lower than the water boiling point--at the dew point. It will not heat the Steamaway/Piggyback/preheater to as high a temperature as would pure steam. Further, when some of the steam condenses, the dew point of the remaning air/steam mixture decreases, and the condensing temperature falls further. The presence of the air also makes the process dependent on mass transfer through an air film, which "consumes" some of the available temperture difference.

Have I answered your questions?

[Beweller]

Haynes,

Centre Acer reports that bubbling nitrogen through the sap gives a different result than does bubbling air. Air resulted in lighter syrup than did nitrogen. Probably the result of a reaction of the sap/syrup with oxygen. Details unknown.

The two obvious effects of air injection are the reduced operating temperature and --possibly, depending on the air/sap ratios--a reduction of the residence time. Convential wisdom says both of the effects will result in lighter syrup.

[NH Maplemaker]

So has Canada outlawed bubbler yet or not? How about any states in the USA? Jim L.

[Haynes Forest Products]

...............................................:) Yes:) ...............................................

[802maple]

It seems that the science behind this came from the same school that global warming is totally caused by humans and that we can turn it around

[NH Maplemaker]

802maple, I'm confused ! Under the new grading standard proposed, isn't tast supposed to have as much of an impact as to whether or not syrup is a Lt, Med, or Dark as color does? If so shoudn't one use that same good judgement when grading syrup made with a bubbler? I would almost bet that no two sugarmaker grade the same in many cases! Jim L.

[HHM-07]

the only advantage of air as far as i can see is for the folks who make candy.

Dick

[DrTimPerkins]

So has Canada outlawed bubbler yet or not? How about any states in the USA? Jim L.

No, to my knowledge it is not banned in Canada. Neither is it banned anywhere in the U.S. to my knowledge. There are some organic syrup production cooperatives in Canada that do not allow their producers to use air injection....but that is because their market is for dark, strong-tasting syrup.

The UVM Proctor Maple Research and Center Acer in Quebec each conducted several studies on air injection. The concensus document we came up with is at http://www.uvm.edu/~pmrc/air_injection.pdf Other publications are in scientific journals and probably not real important to this discussion (unless you are a real glutton for punishment). Please note that the Center Acer studies were done by survey of producers and by lab-scale studies (boiling sap in a pot on the stove and injecting air from a cylinder of air, oxygen, or nitrogen through a custom made air-injection apparatus). The UVM PMRC studies were done in a full-scale maple evaporators (3' x 10'), one of which was equipped with a commercially available air-injection unit operated to manufacturer's specifications using ambient (filtered) air. While our studies agreed on many points, there were some places where the results were somewhat different. Some of these differences are likely due to the experimental approach taken.

The bottom line is that air injection is a tool. Like most things in maple, it is possible for some people to make very good tasting (award winning in fact) syrup, but it is also possible to make some real crappy tasting syrup with it. The main difference is that when you make crappy tasting syrup, it is often very light in color crappy tasting syrup instead of real dark crappy tasting syrup.

A couple of points....

In the UVM PMRC studies, with side-by-side evaportors boiling from the same sap source, air injection:
1. made lighter-colored syrup than non-air-injection syrup,
2. made syrup that was indistinguishable in flavor from syrup made the without air injection,
3. had no impact on the AMOUNT or THICKNESS of niter (scale-type or sugarsand loose-type), although the niter was much lighter in color than that produced in the evaporator without air injection,
4. reduced evaporation rate somewhat, and
5. did not seem to increase off-flavors.

Your mileage may vary.

[DrTimPerkins]

the only advantage of air as far as i can see is for the folks who make candy.

Actually, air injection can make it more difficult for people who make candy or cream. Syrup used for these purposes has to have the right range of invert sugar (a little is good, a lot is very bad). Typically light-colored syrup has a low-moderate invert, and is best for making candy or cream. With air-injection it is possible to make a very light syrup with very high invert level (the reduced temperatures of the boiling sap with air-injection restricts/reduces the caramelization of the glucose that normally occurs upon boiling). If you try to make candy or cream with this stuff (light syrup with high invert), you end up with a sticky mess that won't crystallize properly and thus very unhappy candy makers. Most packers who make candy either test all syrup with a glucose meter, or ask producers to date the syrup (early season light syrup is usually OK...low invert), or both.

A great example of this (especially given that Valentine's Day is just around the corner) is Chocolate covered cherry cordials. They start with solid sucrose based fondant (a sucrose paste--very thick, like pastry dough) and add some invertase enzyme. They cover a cherry with the fondant and dip it in chocolate. Over time, the invertase converts the solid sucrose into a liquid glucose and fructose....giving you a liquid center. Chocolate covered caramel bars are made the same way. Fun through (sugar) chemistry.

[802maple]

Actually Dr. Perkins you can't say that all syrup made with a bubbler is bad for cream and candy. Late syrup with high inverts are not good for making candy, but early syrup will make as good if not better candy and cream. At the Big-e last year most of 30 barrels of syrup we had was made with a bubbler. We made some of the best cream and candy that we have had in years. I personally don't use a glucose strip, a person can taste it and tell if it will make candy. You can't hide late syrup no matter how light it is.

For matter of fact there was a conversation last year about the candy and cream we were making on a particular day about the fact it was nice to see we had good syrup not made with high concentrate and nor a bubbler by a sugarmaker that makes very good syrup. He was shocked when I told him that it was 20 percent concentrate and a bubbler.

Unfortunately this equipment gets a bad rap when someone goes in a sugarhouse and tastes a producers syrup and it doesn't meets his flavor standards. Automatically it is the bubbler and nothing else.

[DrTimPerkins]

Actually Dr. Perkins you can't say that all syrup made with a bubbler is bad for cream and candy.

Actually....I didn't say that. Air injection can make perfectly good syrup for candy or cream (or other uses). It is just that it can also make very light syrup with a very high invert level, which is not good for making candy or cream. I personally don't feel there are any strong counterindications to using an air injection device if your objective to make light syrup.

[treefinder]

i know i went to a guys big outfit last year taps about 25000 taps .you could smell the sourness as soon as you pulled up to the building i was done making syrup for about a week . his color looked like gr.A,but in fact it was bud syrup,i didn't taste it, the smell was enough, he too has bubblers in his with ro and steam away

[sfsshadow]

the only advantage of air as far as i can see is for the folks who make candy.

Dick

not an advantage.cant make good candy from later run syrup,even though its been"lightend"

[802maple]

[QUOTE=DrTimPerkins;96992]Actually, air injection can make it more difficult for people who make candy or cream.

Yeah you did say it, I am sorry to argue but it is right there.

[DrTimPerkins]

[QUOTE=DrTimPerkins;96992]Actually, air injection can make it more difficult for people who make candy or cream.

Yeah you did say it, I am sorry to argue but it is right there.

I said it "can"....I did not say that it always does.


Actually Dr. Perkins you can't say that all syrup made with a bubbler is bad for cream and candy

You stated that "I" said all syrup made with an air injector is bad for cream and candy. I definitely did NOT say that, and do not believe that.

I stand by the statement I did make. I do not stand by the statement you said I made, because I did not make it.

[802maple]

It depends on how one uses the word , but I will accept your explanation as it now puts us both on the same track.