What is the concept of a steam hood?

[SAP EATER]

What is the reason for a steam hood,does'nt it reduce your evaporation rate?

[shane hickey]

Steam hoods are nice to keep the steam out of the shanty I have a 5x16 with hoods and a 6x20 without hoods there's hardly any difference between
them boiling. I have notice a big change in the rafters and tresses, there dark brown every year because the steem sticks to everything. this is where it would be nice to have a set of hoods! On the finish pan I keep it up in the air 2 feet just so you can see wants going on, When you boil long enough you can hear the evaporator talk to ya, and hear where the promblem is, if there is one
shane

[maple connection]

From what I was told a steamhood will hold your heat to keep a better boil.

[Haynes Forest Products]

Only if it was a sealed closed system then you could reduce the rate of evaporation. But you would also increase the tempeture of the liquid. Then the steam would build pressure and it would blow apart:mad::cry::emb: But really we dont create that type of system with the large steam stacks and hinged viewing doors and such the pressure is very low. I think its a happy medium. In a HIGH pressure boiler system the water under extream pressure and the steam is clear and very hot like steam heat with radiators.

Having a completely open set of pans allowing cool air to blow over the boiling sap will cause it to cool the liquid. Im thinking thats why I cover a pot of water im trying to boil.

[Grade "A"]

They also are used to get higher temps out of a preheater.

[maple flats]

They make the evaporation faster, keep the syrup from getting dust, moths etc in the syrup and make a preheater work faster. In fact , many also put a damper in the steam stack and restrict it a little to raise the temp more. I do not. A hood, with condensate gutter and drain also give you hot water to use. When doing a hood, put a catch pan with drain to the gutter, under the stack, to catch what condenses in the stack. The stack will be dripping always back into the pans if you don't.

[SAP EATER]

Thanks to all of ya ,I think going run with out a steam hood this season and see what happens,here's another though you if a person could put the flue pan and the syrup pan under vacuum ,it lower the boiling point and save a whole lot of fuel that would be cool:D:o

[Haynes Forest Products]

Sap Eater thats why I live at 6,500 feet above sea level im Colorado it does help with the boil:lol:

[DrTimPerkins]

...if a person could put the flue pan and the syrup pan under vacuum ,it lower the boiling point and save a whole lot of fuel that would be cool:D:o

This is pretty common in the sugar cane processing industry, as are multiple effect evaporators. Such equipment is available commercially, however most of the vacuum evaporators I've seen are HUGE things (small building sized) and built like tanks....far beyond the scope of what all but a few producers in the maple industry would ever use or afford to have built.

I wouldn't try putting much of a vacuum on a regular maple evaporator unless you want to turn it into a crushed (imploded) pile of metal. They aren't made to deal with any amount of vacuum.

[Haynes Forest Products]

Sap Eater keep in mind that what make Maple Syrup "Maple Syrup" is the boiling prosess. There is a point that if you change the prosess to much your not going to get the original product. In making cane sugar they want tastless white sugar. If you start to alter the prosess to much we get something else......................And a new grading system:o

[ToadHill]

A few years back there was an operation on the ny maple tour that employed a vapor compression evaporator. Also, Lew Staats of Cornell did some research on VCE's. Also, on one of the tours based at Clarkson University a graduate student did a presentation on syrup made with a VCE. All I can tell you from what I recall was that it utilized a vacuum to lower the boiling point of the sap, compressed the steam to raise the pressure so it could be used to boil the sap and resulted in colorless clear syrup that didn't have the characteristic maple flavor. Also, all of the units being employed were military surplus. The technology seemed quite complicated and as I recall was not cost efficient at that time.

[Treetapper]

When someone boils water or cooks frozen vegetables they put a lid on the pot to speed up the process and trap the heat in. When the pan comes to a boil they partially remove the lid. Same concept here. Also a hood is a important part of most preheaters. My hood is just a thin gauge, peaked down to about 5" sides with built in drip gutters. its open on both ends but I know it does help with the evap rate. It covers both pans and lifts up at the syrup end (hinged at the back end) to acces the finish pan.

[sugarmountain]

the pressure inside a properly constructed steam hood definetly adds to the boiling advantage. Most people that run them will agree that a good hood will change the interior pressure a significant amount and of course water boils (sap) at less temp. under pressure. even in small amounts like a few psi. makes a huge difference. Just one more advantage to add to the list.

[Wardner in Tewksbury]

water boils (sap) at less temp. under pressure.

'fraid you got that backwards. Water in Denver boils at approximately 205 degrees due to its elevation and reduced atmospheric pressure. The same principal applies to vacuum drying as in "freeze dried".

If one were to heat sap to boiling in a partial vacuum, the temperature required would be less. Apparently this has been tried but the maple flavor disappears.

[Haynes Forest Products]

Wardner Thats why I live outside Denver at 6,500 ft:lol: But I dont think you would inhance the flavor of Maple syrup doing it at this elevation.

[Beweller]

Vapor compression is much more attractive for smaller installations than multiple effect evaporation. "Small" steam compressors are commercially available.

Note that vapor compression does not imply vacuum. You can boil at 219 F, atmospheric pressure, just fine.

The history of vapor compression evaporation is tied to sea/brackish water conversion, where approach temperatures are very important in the energy balance. In maple sap evaporation where the product stream is small and there is no waste stream, vacuum operation is most probably uneconomic.

[sugarmountain]

ok, i need some help with this one. does the boiling point of water increase under pressure or decrease? the major advantage is obviously the increase in pre heater temp but i could have sworn i saw info from lapierre that stated a slightly higher psi in a hooded evaporator would change the boiling point? i guess i just assumed in the right direction:o Im getting some real education from you guys lately!

[Thompson's Tree Farm]

as pressure increases, boiling point increases. That is why you use a pressure cooker to process canned goods...boils at a higher temp and kills more bacteria.

[findandy]

It was interesting to read your imput. The part I jumped at , was the tour, I was a host on that tour, so you most likely were at a cute log cabin sugar house that was very basic. I know the family that had the vapor compressor (or what ever) I guess it was surplus from a Navy vessel to produce drinking water. Last year he stop in for a chat....He now uses an RO with a small evaporator 2 X by something, still making the same amount of syrup, with less time and less work.

[lpakiz]

1 PSI of pressure will raise the boiling point of water approz 2 degrees. That is what a pressure cap on your car radiator does. If your pressure cap is rated at 10 PSI, your (Nominal) boiling point will be 232 degrees. Since we WANT to boil off steam, we do not want pressure holding it back, even if it does raise the boiling point.

[SAP EATER]

Wow did I open up a good topic here !! :o

[kiegscustoms]

Long walk to the sugar house from Denver ain't it Haynes?;). After having a steam hood I would never run a flue pan without one again. Like using an RO or a filter press. Once you have one you are lost without one. Besides the comfort factor. I have been in a few sugar houses without hoods and you can be standing next to someone and only be able to see their feet. Depend on the weather though. Dud - remember your nickname for Lapierre?:D

[3rdgen.maple]

Been in a few places where I wished I couldnt see....... oh nevermind:lol:

[kiegscustoms]

Been in a few places where I wished I couldnt see....... oh nevermind:lol:


10-4 Driver

[Wardner in Tewksbury]

I am impressed with the practical and theoretical knowledge base on this forum. The talk about pressure, temperature, and evaporation in regards to sap brings up a reduction process potential that might work.

What if 2000 gallons of sap were pumped into a retort that would heat the sap way above its boiling point. The outlet of the tank would go to a pump and orifice similar to a water-jet cutting machine. The high heat/high pressure sap exiting out of the orifice would be regulated so that some percentage of the sap would turn to hot water vapor for preheat and the balance would go into maple product containers. Might not even need filtering or other processing for different maple products.

Yeah, I know I am just dreaming and the above is just a transitional phase. Eventually I think syrup, not sap, will be collected from the trees. At the end of the season, the farmer will drive out to the sugar bush and collect a gallon of finished product from each tap.

[Haynes Forest Products]

Wardner They do that in tall hot towers and all you get is tastless sugar. Thats how they condence milk and its part of instant coffee. BUT once again Maple syrup is made by boiling Maple tree sap and part of that prosess is COOKING Maple sap and boiling it to remove large amounts of the H2O

I believe Shlitz Beer came up with a brewing prosess that eliminated about half the BREWING.....and used a few chemical addatives to speed up the BREWING prosess and they changed the formula:rolleyes: That worked well for them. Went from Number 1 to ZIP ZILCH NADA

[Beweller]

If my memory serves, it was demonstrated about 60 years ago that low temperature processing of maple sap (eg, vacuum evaporation) produced a sweet, colorless, generally tasteless product. It was also demonstrated that heating this product (without evaporation) converted it to maple syrup.

This seems to be rediscovered about every 10 years.

Flash evaporation requires considerable recirculation, as 10 degrees of liquid superheat will evaporate something like 1/100 of the liquid.

Spray "drying", where a liquid is sprayed into a hot gas (air or superheated steam) is a different process.

[sugarmountain]

ya i remember keenan, back ordered again right? ya hoods are awesome my sap comes in like 180 mostly and the stream is manageable. No more nail dripping on my chair !

[Sugarmaker]

Whats in your Hood? Steam!
Like others said wouldn't be with out them. I am dry and can see!
But I don't mid going into a place with no hoods takes me back in time like the "way back" machine:)
Chris

[SAP EATER]

Well i guess its a good idea to keep my steam hood on,the idea of vacuum evporation seems like it would a great idea if you had lots and lots of money,time,a very big biulding and want to make clear,flavorless sugar syrup.After thinking about more I beleive that the flavor of maple syrup is not only produced by the tree it self but also by the evaporation process that we all use and which part of it is carmelization.I work one of the biggest food companies in the world and I've seen alot of processes in which they use carmelization in part of the flavor process. :cool:

[sugarmountain]

I agree sugarmaker, i still like some steam in the sugarhouse. When i was a youger lad my father ran two 5x14 leader drop flues. No hoods back then, lots of steam memories. We still have the front pan to supply our need for steam and the rear hood stack goes into the cupola(sp?) so still pretty old fashioned.

[Monster Maples]

Quote: I believe Shlitz Beer came up with a brewing prosess that eliminated about half the BREWING.....and used a few chemical addatives to speed up the BREWING prosess and they changed the formula That worked well for them. Went from Number 1 to ZIP ZILCH NADA

No Haynes, I think they just renamed Shlitz to Natural Light. You can drink it, goes down smooth. The next day it has the same effect as the Shlitz. To the office to see John and do a whole lot of paperwork.:lol: