GE Merlin RO for Sap First run

[Brent]

Well after a couple runs on the new evap I felt confident enough to get the GE Merlin RO into the sugar shack for a try.

I started out with a couple hundred gallons of cold ( ice on top ) sap that tested 3% just the same as I had been running the last few days.

A single pass through the Merlin kicked it up to 3.5 to 3.6% Not great but a real improvement

The permeate was checked several times and it was 0 or 0.1. Not easy to read the difference and I would need someone to tell me how to read the meniscus on a hydrometer to be more accurate.

I left the RO running with the condensate feeding back into the 200 gallon tank while I got the firewood ready, went to woods to collect sap etc so it had about 6 hours before I fired up the evap. At that time the 200 gallon tank had gone down some but the remainder was up to 4%. I lit the fire and alternately pumped the condensate into the overhead feed tank or back into the main storage tank. By 10:00 tonight I was boiling 4.6% sap.

The permeate flow dropped of worse than I had hoped for because of the cold water. The factory spec gives the temp range from 40 as a bottom.
I had the premeate going into a 5 gallon pail and it was taking about 40-45 minutes to fill it, so say 6 1/2 gallons an hour.

Over the day it dumped 86 gallons that I did not have to boil.

Not a rocket ship, but 86 less gallons in a day from a $ 400 RO not including pump. Pretty good.

Tomorrow I will flush out the preservative from the second Merlin and put it on line when we get more sap in the afternoon. I had sized the pump that outputs 80 PSI, optimum for the Merlin, so it would run 2 Merlins.

So far, it looks like it will save a lot of firewood and a lot of boil time over the balance of the season.

[MaplePancakeMan]

86 gallons of the 2x6 saves you atleast 3 hrs of boiling each time, and if you figure even making 10 dollars an hour doing something else thats 30 bucks each boil atleast 12 boils a season and thats 360 bucks. Add in the fire wood and you've recouped your investment in easily a year.


Kudos on the merlin. That would be really good for someone with a halfpint to run along with it as it produces about what that boils out and hour.


So what are you going to do with it turn it on at night before a boil and let it run for 6-8 hours before boiling so you can build up enough to boil with?

[maple flats]

I might have to consider trying a short bank of those. Everytime i can afford it, I could add another in parallel. This could save some wood, boil time and give more fresh water for cleanup. Let us know at the end of the season how you think it was over the longer run.
Dave

[Gary in NH]

Hi Brent,

Glad to hear the Merlin is working. As you have experienced the permeate flow will decrease as the temperature of the sap decreases and vice versa. Your concentrate flow stays the same because it is controlled by a fixed flow restrictor. The permeate flow is controlled by 1) feed pressure and 2) the density of the solution pasing through the membrane. As the temperature of the fluid drops the fluid becomes more dense and passes through the membrane at a slower rate. If you can somehow warm the sap feeding into the RO you will increase your permeate flow. You may want to also try experimenting with increasing the feed pressure to see what happens. As an FYI for comparison of output calculations: If you take ml/min x .40 you will get the gallon per day (24 hr) output.

[325abn]

It sounds like a hobby RO has been invented!!!!!!!!

[325abn]

86 Gal is about 4 hours for me. I think I may put one of these bad boys together for next year.

[Gary R]

Good job Brent. I'm going to have to start collecting stuff;) . Every day I work on machines that have parts alot of Mapler's could use. Liquid ring vacuum pumps, Procon 170psi pumps, even 1500W, 120VAC, stainless heating element in a stainless housing, used to heat fluids. We throw this stuff out all the time when units are replaced. Usually everthing is in good working order.

How will the cleaning process work or will you replace membranes every season?

[MaplePancakeMan]

Gary R whats that stainless heating element in a stainless box? Does it have an inlet and an outlet and how big is it? That could have multiple uses small preheater for the evaporator or for an ro such as the merlin which would drastically increase the production of the merlin. Let me know what those are like i'd def be interested if you were to come across some.

[Gary R]

The units are a low temperature sterilizer, they are in hold about 3-4 gal. of water. They use a flowjet circulation pump. The actual heater housing is about 2" diameter X 1' long. There is an inlet and outlet on either end and each is about 1" in diameter. We connect to them with hose and clamps. I just threw out an entire machine last week and probably 4-5 in the last year. I know where a couple are in a closet being parted out. It will take me some time, but I know I can get a few. I would ship 1 to you or another RO tinkerer for free. Just let us know how they work.:)

[MaplePancakeMan]

Just let me know if ya find one and pm me or something like that. I think that if it didn't heat the sap up too terribly much it would be extremely beneficial on an RO and as long as one is boiling it relatively soon or like myself or Brent will be doing is basically running it as the evaporator goes there should be no worries about bacteria growth.

And i'd definitely let you all know how it works. All depending on how much it can heat it up but at 77 degrees are what the specs of my machine are in, sap is 35 at best so it immediately cuts that in half.

[802maple]

Experimentation has been done by warming the sap to make the r.o. more efficient but like was said it has to go directly into the evaporator from the r.o or bacteria wiil grow rapidly. Keep on testing.

[Brent]

Yesterday we collected just over 200 gallons and have it in the storage tank. Expect to get about the same today. Going to get both Merlins on line pretty soon.

The idea of heating the sap to improve the RO performance needs some further work. These units are not at all the speed of the big $6000 to $10000 rigs. So heating the sap would mean holding the temp up for a long time while the mini RO's do the job. I don't know where the trade off comes on bacteria growth and increased efficiency. Certainly the test I did in the kitchen with cold well water had much much better permeate flows. The energy costs of heating sap just for the RO and losing the heat in the storage tanks strikes me as pretty futile. I think you'd lose more heat, and therefore wood or oil, than you would save with the concentration.

Maybe the solution is to put a big storage tank in the sugar shack. Run the sap through UV, thru a 1 mircron filter, heat it to 50 degrees and keep it there while it gets re-cycled through the mini RO's for half a day. Then into the evap.

For now I'm just going to turn on the pump and let it go all day. If the pump is a 1 Kw unit and it goes 8 hours and electric cost is say an average 10 cents per KW hour, I can take the total energy bill of 80 cents. Around here electricity is only 6 1/2 cents per KWH.


This is a great trade off.

I don't know what is available locally in a less expensive pump than the one I got. This unit is inverter controlled with a pressure transducer which through a bit of logic controls the pump speed to give exactly the pressure you need, in the case of the Merlin, that's 80 PSI. Lower the pressure and it will allow more sugars to pass. The pump can be ordered to run on 110 or 220. Not switchable in the field because the inverters are not dual voltage. The pupm specs can be seen (pdf) at
http://www.walruspumps.com/products.html

I paid just under $800 for the TPH2T6KSIC, stainless pump and multi stage impeller. I paid to fly it in from Taiwan. I did not check the price for the US dealer in California where the pdf download comes from. I'm sure it will be a lot more. We bring a container of machinery from Taiwan every 4 to 6 weeks and a little pump like this can essentially travel free. There would be about 5% US import duty. If anyone was so inclined, I could bring in some more for less under $ 1000. There could well be alternatives. I just loved the controllability of this pump and soft start with the inverter for the sugar shack where power is limited.

I also got a simple 3/4 Hp transfer pump from Walrus that is 110-220 and they could be available for maybe $100 to 125.

More results and impressions will be posted tonight after run both for the day. Right now its about 18 deg F outside so I'm going to have to heat the valve on the storage tank to get things started.

[Brent]

Saturday Update

this morning we rigged in the second Merlin and fired it up at about 11:30 AM

Now at about 2:30 pm, 3 hours later, we have 6 water jugs = 30 gallons, of pure permeate. Tested with the sap hydrometer. ZERO.

We have it just re-circulating into the storage tank that was a bit over 200 gallons when we started. Tested it before starting the RO and it was 2.9.

The concentrate coming back in was about 3.5

The important thing is that about 1 hours worth of boiling was saved by running it for 3 hours while we cleaned the syrup pan etc etc..

Going out to light the fire. Expect we'll be done "yesterdays" sap in about 4 to 5 hours. By then the Merlins will have saved us 3 hours of boil.

Bottom line. I think this was a good investment. Later today I'll take some pictures and put them on our web site.

Oh yeah ... the little pump is still holding bang on 80 psi.

[MaplePancakeMan]

i know its been said before but with the merlins. If you had that heating element (which holds only a few gallons at a time so you aren't opening bacterial growth up to all of the sap) and you are recirculating it back into 35 degree sap you will effectively cool it to slow bacteria growth and then if you are boiling it a short while after you shouldn't have to worry about it too much. Additionally If you used a Wort chiller to chill the concentrate you would pretty much eliminate the bacterial growth.


I could be wrong but i could see it working

[MaplePancakeMan]

So with both merlins your doing around 15 gallons an hour of total sap processed between permeate and concentrate? Thats pretty decent. Even just saving 3 hrs of boil time each time is worth it.

[325abn]

Well I am convinced that this hobby RO will be ideal for my 2x4 raised flue.

I will be starting on this in 3-4 weeks. It will certainly make my hours out here easier to take.

Thanks for posting all your results

[Brent]

We started the Merlins in the AM as reported above. We have a touch over 200 gallons of 2.9% when we started. We added a bit today, a poor run, and
between the Merlins and the evap we polished off 255 gallons. Got 10 left in the overhead and that's it.

The boil started at 4:00 and ended at 10:00 Just about 44 gallons an hour on a mickey mouse RO system and a 2 x 6 evap

Maybe we can call this "Ramini" instead of Ramona. ?????

Still getting lighter that Ontario #1 extra light .... off the chart.

PS: Also the first day to go really automated on the draw off. Is that scary.
And the ****ed ball valve is so huge that by the type the syrup goes through it, it has lost so much heat
that you can't use the 211 degree mark. Had to go to the correction chart and that did not inspire much confidence.
But in the calm of the kitchen tonight it looks like we got about 6 1/2 - 7 gallons averaging 1 degree heavy.
Cool. Easier to add and dilute than go back to a boil on a finisher.

Going to sleep easy tonight, hoping for a good run tomorrow. Need it. Nothing left.

I have posted some pictures of the RO to our web site on a page without a menu link.
http://www.hhrm.ca/duffyslanemaple/Merlin/RO-system.html

There are also some new pictures of the sugar shack on the home page.

[MaplePancakeMan]

Brent, i just took a look at your Evaporator and wow am i jealous. I remember when my cast front and rails were all shinny. Now from outside they have oxidized. I am going to refinish it as its coming up on 4 years old I'll probably have it soda blasted and clean it up. Anyone have any good ideas for this?


I want to keep the stainless shinny but i need to sand down the rest and and repaint it.

[Gary R]

Brent, I went to your home page. That's a fine looking place you have there.

I hope you don't mind my thoughts on the RO project. I have a idea on the heaters that I can get. Back in the day, I was an electronics guy. We sometimes used a variac (adjustable transformer) to control AC voltage. They come in all sizes but the one I have (had?) would take 120VAC in and you could adjust it from about 30 - 150VAC. Since the heater is a resistive load, you can control the heat (watts) by the voltage applied to heater. Sap flow and temperature would be fairly constant to the heater. With a temperature gauge on the output of the heater you could easily adjust the temperature of the sap to the RO. This way you wouldn't need fancy controls to turn the heater on and off. Just need to find a variac. Small amount of sap would be heated for a few minutes. Then send concentrate back outside to cool.

Keep us posted!

[Brent]

Gary
The idea sounds like it would work, but a 110 V line would not raise the temperature very fast. They concentrate flow is 2 gallons a minute and would be constant even at low temperatures. It would take a lot of power to raise the temperature of 2 gallons every minute just 10 degrees. And the factory spec says minimum operating temp is 40.

I think it would be a lot of expense when the simple way is just to let it run all day and all night.

Today we started with 75 gallons of 2.6 % sap and added 105 more gallons during the day. I left the twin RO's running from 10 AM to 9 PM. We have 75 to 80 gallons in the tank and its now 6%. That remove 100 gallons at a cost of 11 hours at 1 KW per hour at say 10 cents .... $ 1.10 And I never lit the fire !!!

If I had a gangbusters collection day and the tank was near the top ( 275 gallons) I just would have left it go all night.

This is a cheap, sort of home brewed system that appears to work. The only unanswered question is, how long will the membranes last.

[Amber Gold]

I've been following this thread and think that the results from your last post are great. If you let it run any longer do you think that you would get even better results and maybe get to 8% or 10% sugar? Also did you test the waste water for sugar content from this last run? If the membranes did fail would you be able to swap them out with membranes from LaPierre or somebody else?

I was looking at your website and you've got a nice setup. I was thinking of getting a Phaneuf raised flue pan for my 2x6 and was wondering if you were happy with yours and what you are getting for evaporation rates?

Thanks

Josh