Scrubber Media - the cost to fill thread

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snoman701

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Oct 8, 2016
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Location
SE MI
So there's a lot of information on the forum about scrubbers. There's also lots of posts about what people fill their scrubbers with, most seem to favor the use of stuff that they can find easily like bioballs, marbles, cut PVC, etc.

I am finding that I'm spending too much time looking for the alternative route, when the answer has already been hashed out in industry, and just costs a few bucks more...or less.

I'm going to do a 50 gallon drum, with sprayer at the top, so figure about 30 gallons of balls, or 4 cu ft.

Bioballs, $75/cu ft (Dr's Foster & Smith, $50/5 gallon)

Tri-Pack 1" polypropylene balls, $45/cu ft (Tri-Mer Corp, 10 cu ft min order)

Cut PVC, I can get a whole bunch of it from the local recycle place for next to nothing, but then I've got to cut it. Thinking about loading my van up with used PVC, and filling a 1' square box with 1" long pieces makes me think that it would cost more than $45/cu ft, even if the material is less.

Now, bioballs still have greater surface area, but they also have much lower void space, which means that the pressure drop across thru the scrubber increases. A suitable poly blower is still $1800 for the average hood.
 
I saw that in one of your threads. I spent quite a bit of time searching the forum, couldn't sleep the other night.

I've racked my brain trying to think of things around here that I can get cheap or free, that will still give good air flow. My conclusion is it's cheaper to just buy them.

There are a lot of alternatives out there, but the quantity is what kills me...I even considered the "loofa" scrubby that's hanging in the bath (not sure about acid resistance, didn't care enough to try, but unraveled, it seems like it would work ok in a flooded column)
 
It mainly must be resistant to the NaOH. About any PE, PP, PVC, etc. Nylon is bad with acids, but I don't know about NaOH. You need something inert that has a high surface area per unit of bulk volume. If I remember right, those saddles made for scrubbers mathematically have the highest surface area per unit volume, of any other shape, but they're quite expensive. Surely there is some sort of cheap PE "thing" made in the US that has a lot of surface area. Every manufacturer has rejects and waste. Maybe something like drillings.

If you had a lot of spare time, you could cut small plastic pipe into small pieces. What if you hammermilled plastic pipe , or what?, using about a 1" to 1-1/2" screen? Tree limb shredder? You could screen out the fines. Just thinking out loud.
 
This chart may help Chris.

http://www.plasticsintl.com/plastics_chemical_resistence_chart.html
 
My other plan was to use cut up PP barrels. I'm in the process of cutting up about 30 of them for the melt shop I spend time at. They'd work fine for the submerged scrubber, but for an actual gas scrubbing tower, I want to have as little resistance as possible. Then I started thinking about how long it would take me to cut them up in to nice little sizes. Plus, I'd have to fix the bandsaw first. And I'm back at buying the media being the cheaper option :D

If I was just scrubbing gasses from closed reactions, I could get away with just the submerged system, but I really want to be able to use a poly tub cement mixer, and for that, I'd figure I have to fit it with a really tight fitting lid (which is going to be a bit of a pain) so the eductors can keep up, or really low resistance tower. I can titrate nitric feed to match capacity.

For the eductors, I bought three of the nalgene "disposables", I already have a few of them around here. I plan to just gang them all together.

I have to do some checking on the pump, but I know the melt shop has been using a pool pump for quite some time with success for providing vacuum (through a gang of disposable aspirator/eductors). But I don't think he's running at as high of pH, I'll have to check. If I have to spend the money for a sealed caustic pump, I have to spend it. Dealing with frozen bearings and leaking seals isn't fun.
 
One place I'd strongly recommend checking is if you have a scrap yard that takes plastic. We have one that I used to do work for on occasion, but they don't let the public buy from them, and my contact there quit. They always had goodies like thread spools and crap, in gaylord quantity.
 
goldsilverpro said:
Every manufacturer has rejects and waste. Maybe something like drillings.

It's true, but it would have to be the right manufacturer too. I did a summer internship with an injection moulding company. Lots of rejects, but they were ground right back up and fed back in to the machine. It was actually cool, the automatic sorting machine would pull the bad ones and just feed it in to a small granulator, then meter it back in to melt.

Actually, they were making disposable food containers and utensils, which will often be polystyrene. Forks have a reaosnably good shape in terms of surface area vs mass. Interlock the tines of two of them and it's a nice little thingie.

Out of the polymer companies I've worked for, it's always the research and development guys that generate the most waste. All mold testing was done on virgin material only as it has more consistent flow characteristics.
 
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