Stage Vane

Stage Vane

 

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Engineering related (esp. water treatment)?

I was hoping someone could give me a good description of a couple of things:

(1) What is an "antiscalant" used for with regards to RO (reverse osmosis) and what are some typical compounds used for this?

(2) How does a rotary vane pump work? What are the major types of pumps used in the chemical engineering industry (is there some way to classify them?) and where can I find a good free online resource for pump selection?

(3) In a small-scale RO equipment (eg. for purifying drinking water from bore water) what are cartridge filters used for? I am slightly confused which stages (ie filter/RO/aniscalant dosing) are used for physical and chemical treatment....

Thankyou! John.

I'm a talker and I could explain most of this...but it would take volumes of pages and then you would have to decide if I knew what I was talking about.
Here is a great link that is a good starting point to look up most of what you need:

http://www.engineeringtoolbox.com/

Just to start you in some direction:
1. An antiscalant is what they do to pre-process the water before it enters the RO unit. The scale in the water comes from dissolved solids that is present in most water sources and is primarily calcium and magnesium compounds. The RO membrane does get clogged up and so the water is pretreated before it enters the unit to take out the easy compounds and help the RO unit process more gallonage. RO units are a lot slower than sodium based water conditioners, so water conditioners replace the calcium and magnesium ions that can deposit on the membrane and clog it, and replace it with sodium ions which won't deposit on the membrane and will get ejected with the waste stream.
Now a days they aren't using chemicals especially for drinking water applications, they may use them for industrial applications, I'm not sure. But it is very quick and efficient to remove limescale with a salt based water softener.

2. Rotary vane pump is just a pump that is built like a centrifugal pump, but the spinning impeller is made with expanding vanes that are in an oblong cylinder so that the volume of the solution being pumped expands after the inlet and then the vane collapses as it reaches the outlet which squeezes out the extra volume that was initially drawn in.

http://en.wikipedia.org/wiki/Vane_pump

3. Cartridge filters are used if your water source isn't that "hard", meaning it doesn't have a lot of calcium and magnesium in it, so a water softener isn't needed for pre-treatment. Cartridge filters pull out suspended dirt, rust, and sand. Cartridge filters usually have activated charcoal in them also, especially if there is chlorine in your water used for the bacteria. The charcoal pulls the chlorine out, because the chlorine will spoil the RO membrane in a hurry and corrode it.

Bottom line, most of the time you only want to use the RO unit for desalination work if that is your only choice for water. If you want it for home use, then only use a small unit that supplies drinking water only (gallon or two a day). Use a cartridge filter and water softener for the other 98% of your water needs. RO units waste a lot of water and energy to get that high quality water. But you don't need RO water for industrial use (except food plants) or any non-drinking application

Holset VGT Turbo HE351VE Controller Development Stage 3


 

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