membrane addiction questions

[calvertbrothers]

I have a homemade ro that does between 200-250 gph at 6% sugar after one pass, that has 2 membranes and I want to add one more. what would I need to make it work? a bigger pump? And what benefits will I get out of adding another brain?

[BreezyHill]

There are a couple of ways to do this:
1, have your flow from Vessel #2 go to a booster pump and directly into a third and possibly forth vessel to further increase your concentration flow. This is running in series.

2, have a second pair of vessels that tee off of a larger pump to increase your flow. This is running parallel.

3, you can have a second complete unit with 2 vessels. This is a primary secondary setup.

All options have their own merits; but one major factor is the flow rate of the current pump and what is the bottle neck or the weak point of the current system?


I am in the same quandary as you...I have an old RO that was built when the process was very new, 1982. The pump is a 5 hp piston pump fed by a 1 Hp deep well pump.

This was setup to run 2 4x40 vessels. Last season I installed 2 new vessels and xle membranes(mbs). The old mbs & vessels were missing. The records on production of the unit from new show the unit making 10-12% on one pass at 500psi. I ran the unit at 250 and was getting in the 6-8% range but more water removal per hour.

My bottle neck is that my mbs circulation flow is enough for 4 mbs at 35+ gph. So I need to decide weather I add a second pair and run them parallel or a third in series.

Currently I batch run and get the evap going when I have enough product to fire the evap and have an hour of capacity run in the head tank and fill as needed while batching. When the mbs start to loose flow rate I can just increase the flow off the concentrate and flush across the mbs and in 2-3 minutes have the capacity back to where it was at the start. If I increase my mbs space to much I will loose this fast flush ability and loose capacity. my CDL manager recommended an 8" membrane as it has capacity and area of nearly 3 4x40s and will keep my costs down and utilize the current unit with a slight modification to the back of the unit to keep it enclosed so that it is a self heating unit in the off season so it will not freeze. Then I would build a second unit to use the 2 current vessels.

Since you already have a good working unit and the addition of a pump and two vessels to run in series would be an easy build I would go that route. You can use SS quick locks to add the expansion when needed and use the current system until the expansion is built. Then if desired the expansion could be turned into a second stand alone unit with the addition of flow meters, prefilters, and supply pump as needed.

This way if one pressure pump craps out you can still run until repairs are made. I like to have a backup plan.

Murphy's Law is a real downer...Things will go wrong at the worst possible time.

Ben

[calvertbrothers]

Do you know where I can find a 4"x40" pressure vessel and membrane for a good price?

[SWEETER CREATIONS]

Atlantic R/O for the membranes and Dultmeier for the vessels I think they were about $ 90.00 each