Brent
03-01-2008, 11:50 PM
Well, while sitting chewing my finger nails waiting for things to start happening, I decided to test run one of the two GE Merlin RO units. I set one of them up on the kitchen counter, filled the sink with tap sap, hooked up the great variable speed / constant pressure pump I found, and let it rip.
At the optimum membrane input pressure of 80 psi it pumps out 2 litres of clear water in almost exactly 45 seconds, or roughly 0.8 US GPM. The factory spec claims output of 0.7 US GPM My test water was cooler than the factory spec.
If the output drops to 1/2 Gallon at the colder temps of sap, and I have two of them running, I'll be dumping 1 GPM or 60 gallons an hour. That's roughly double what I expect the evaporator to boil off. Between the RO and the evap I'll be able to process nearly 100 GPH of sap. Last year that was all I could manage in a long exhausting 18 hour boil on the half pint.
Not to mention that if I get enough sap I could let the RO fill a storage tank in the night.
So I think, so far, it looks good for the cost. The question remains how much performance will be lost, if any, when the sap with sugars starts to go through. More news soon, real soon I hope.
LATER:
I decided the other half of the equation was how much concentrate came through. 4 Liters a minute or about 1.06 US GPM
So roughly 1.8 GPM input to dump 0.8 GMP of fresh water. Ratio of 0.4444 So that should take 2% sap up to 3.4% roughly. in a single pass
through the system. Since it is going through so fast, as the day progressed you could put it through multiple times as you continued to boil
and by the end of the day the take off rate would be pretty respectable.
AND THEN DAY TWO
This morning, sunup Sunday, I re-filled the sink with the coldest water I could get and the results were quite different.
I also discovered that I had mis-read the pressure gauge. I thought I had it a 80 psi last night but in fact it was only at 60. Don't try this at home.
Or at least don't try this at home after midnight when you're pooped out. The fumble factor intrudes on the science.
The beauty of this special pump became evident. Just lean on the UP arrow until the display said 80. Done. Actually the pump is in BARS not PSI
and that's how I got screwed up. The RO came with a dial gauge and that's what I mis-read. The 60 looked like 80 without the glasses.
SO at 80 psi and At 50 deg F the flow of permeate, ( pure water removed ) dropped to 2 litres in about 65 seconds, almost half of the rate I got last night
with warmer water. Concentrate flow changed to 2L in 20 seconds. So not only did the removal rate change but the ratio changed. This was not unanticipated
because the spec sheet for the RO indicates a higher rejection rate at higher pressure. It seems backwards but that's the way RO's work.
In US Gallons: concentrate 1.58 GPM and 0.52 GPH of permeate. So now we're down to just over 30 GPM of water removed.
This just about matches what I expect from the new evap. If I run the RO equal hours to the it should just about double my syrup production .... but that is
for just one RO and I'lll be putting a second one on in series. The pump should still be able to give me 80 psi with both.
BUT the sap will be still colder than my test today. Add the second RO, Take away some efficiency for even colder water, and it should still be a double.
And then the fudge factor for the fact that we can start running the RO a soon as we get the first sap in the morning and before we light the fire and I think
we'll be even more concentrated.
Overall I'm expecting to about triple the gallons per day we can handle just by adding this home system.
Costs Each RO retails for about $ 400.
The pump was about $800 but that was for a one off special purchase from Taiwan. If I brought in a couple dozen at a time in cases with our machinery
we might be able to cut that down. We also may find a cheaper style of pump. I wanted to try this because of the inverter technology. Soft start up power surge,
very little power draw. Minimal "thrashing" of the sap because the pump would only run as fast as it needs. If we used a simple multi stage direct on line pump with a mechanical pressure
regulator, I think that cost $ 800 could be cut by 1/2 to 1/3 but power consumption would go up and if you're on a generator, that counts for something.
Cost of my rig as testing is therefore about $ 1600. New membranes if and when needed. $100 each x 4 for the full set.
Lots of variables yet to test. But I am still thinking it's going to be pretty good bang for your buck.
Stay tuned.
At the optimum membrane input pressure of 80 psi it pumps out 2 litres of clear water in almost exactly 45 seconds, or roughly 0.8 US GPM. The factory spec claims output of 0.7 US GPM My test water was cooler than the factory spec.
If the output drops to 1/2 Gallon at the colder temps of sap, and I have two of them running, I'll be dumping 1 GPM or 60 gallons an hour. That's roughly double what I expect the evaporator to boil off. Between the RO and the evap I'll be able to process nearly 100 GPH of sap. Last year that was all I could manage in a long exhausting 18 hour boil on the half pint.
Not to mention that if I get enough sap I could let the RO fill a storage tank in the night.
So I think, so far, it looks good for the cost. The question remains how much performance will be lost, if any, when the sap with sugars starts to go through. More news soon, real soon I hope.
LATER:
I decided the other half of the equation was how much concentrate came through. 4 Liters a minute or about 1.06 US GPM
So roughly 1.8 GPM input to dump 0.8 GMP of fresh water. Ratio of 0.4444 So that should take 2% sap up to 3.4% roughly. in a single pass
through the system. Since it is going through so fast, as the day progressed you could put it through multiple times as you continued to boil
and by the end of the day the take off rate would be pretty respectable.
AND THEN DAY TWO
This morning, sunup Sunday, I re-filled the sink with the coldest water I could get and the results were quite different.
I also discovered that I had mis-read the pressure gauge. I thought I had it a 80 psi last night but in fact it was only at 60. Don't try this at home.
Or at least don't try this at home after midnight when you're pooped out. The fumble factor intrudes on the science.
The beauty of this special pump became evident. Just lean on the UP arrow until the display said 80. Done. Actually the pump is in BARS not PSI
and that's how I got screwed up. The RO came with a dial gauge and that's what I mis-read. The 60 looked like 80 without the glasses.
SO at 80 psi and At 50 deg F the flow of permeate, ( pure water removed ) dropped to 2 litres in about 65 seconds, almost half of the rate I got last night
with warmer water. Concentrate flow changed to 2L in 20 seconds. So not only did the removal rate change but the ratio changed. This was not unanticipated
because the spec sheet for the RO indicates a higher rejection rate at higher pressure. It seems backwards but that's the way RO's work.
In US Gallons: concentrate 1.58 GPM and 0.52 GPH of permeate. So now we're down to just over 30 GPM of water removed.
This just about matches what I expect from the new evap. If I run the RO equal hours to the it should just about double my syrup production .... but that is
for just one RO and I'lll be putting a second one on in series. The pump should still be able to give me 80 psi with both.
BUT the sap will be still colder than my test today. Add the second RO, Take away some efficiency for even colder water, and it should still be a double.
And then the fudge factor for the fact that we can start running the RO a soon as we get the first sap in the morning and before we light the fire and I think
we'll be even more concentrated.
Overall I'm expecting to about triple the gallons per day we can handle just by adding this home system.
Costs Each RO retails for about $ 400.
The pump was about $800 but that was for a one off special purchase from Taiwan. If I brought in a couple dozen at a time in cases with our machinery
we might be able to cut that down. We also may find a cheaper style of pump. I wanted to try this because of the inverter technology. Soft start up power surge,
very little power draw. Minimal "thrashing" of the sap because the pump would only run as fast as it needs. If we used a simple multi stage direct on line pump with a mechanical pressure
regulator, I think that cost $ 800 could be cut by 1/2 to 1/3 but power consumption would go up and if you're on a generator, that counts for something.
Cost of my rig as testing is therefore about $ 1600. New membranes if and when needed. $100 each x 4 for the full set.
Lots of variables yet to test. But I am still thinking it's going to be pretty good bang for your buck.
Stay tuned.