First time post. I've been researching and building (piece by piece) for a long time. I'm almost done with a GL style push pull and recently was able to get a hold of some old air dryer towers. I got rid of the old desiccant and have modified them appropriately for fittings and strainers. These towers were originally set up for a dry system and only has 2" pipe plugs top and bottom for changing media. Am I kidding myself by thinking I might be able to change wood chips and sawdust through that small of a penetration? Should I just cut my losses and go a head and manufacture some hand hole covers, cut some bigger holes and do some more welding?
Hi Bill, no I wouldnt use them for woodchips or even sawdust. When I started using shavings I had a 90L resin tower with a 5" hole and it took ages to empty the old shavings. It was so bad I gave up on it after just one change of shavings. Now I use a 200L plastic garden water drum, which is so easy to use and empty. Get one at a garden centre, and choose one with the largest lid.
A 2 inch hole is going to be very difficult to deal with.
If you design your tower where the top opening is same size diameter of the filter tower, and the sides are slick, and it can handle 125psi, you can push the sawdust out using air pressure. It will push it out like a big hydraulic cylinder. I have a 12 inch diameter 6ft tall tower and I can change the sawdust in about 15 minutes and be back filtering.
Thanks for the input. Is the problem with change out compaction/expansion of the wood chips or do they just hang together and not want to come out?
Its both - the stuff tends to clump a bit due to the absorbed soap and glycerol as well as compaction.
Jehu is right on!Its both.
I know its been said before, but push the fuel up through from the bottom to the top. People say that this helps, and it makes sense. I cant say for a fact it makes a difference, but I have always filtered from the bottom and pumped up.
With my new chip set up it now goes from the demething tank to the top of the chip drum and then filters at the bottom to then flow up to the twin Purolite PD206 resin beds which are reverse flow tanks and as a fianl filter I use a CAT 2 micron fuel can.
It's overkill, but works well.
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I thought Hannes might have jumped in by now. He is trying wood shaving filtering, and had a bit of a problem emptying the shavings from his drums. He now fills orange bags which are woven from polypropylene, I think, dumps those in the barrels and when finished it's a piece of cake to pull them out, dump or burn, although they burn something fierce. Jim.
When I had a resin tank I tried upflow but it wasnt nearly as good as downflow. However, no more pumping for me, I swear by gravity.
Thanks for all of the input.
I've been getting a little impatient lately and almost had myself talked into putting these towers on line with just the original pipe plugs for changed media. That would have been a big mistake that I would have regretted. I am now going to slow back down and modify the towers so they have removable end bells on the bottoms. I've seen several of these in some of the other members' setups. At the time I thought it was an odd way to do it but it makes good sense in this situation. I want to stick with the towers because they fit my overall scheme nicely, but I definitely understand and see the benefits of using drums (I'm very sick of welding on drums).
I'm planning on using a four tower lead/lag setup and only changing chips on one tower at a time as samples, flow and pressure dictate. I am hoping to eliminate the intermediate settling tank step. I am set up for 75 gallon batches with a total tower capacity of about 200 gallons. That should give me enough total volume to always be one batch behind on filtered output giving max residence time to the previous batch. I'm going to use a low volume pump of 1 gpm straight out of the processor after WB demeth and draining of glyc. Still kicking around up vs down flow, pros and cons. I know I will go through chips a little faster by not settling, but I have access to a lot of small sawmills and pretty much unlimited supply.
Have you tried hooking up to a garden hose, the wood should float out the top and the glycerin and soap should soften.
Yes, I noticed thay the wood shavings compact with use. This came to light when I had to dig out the compacted stuff. Sticking your head into a meth fumed drum to dig out chips is just not on. So at first I turned the drum upside down and even then the chips are reluctant to come out. I ended up making one hell of a mess. I also burned some of the spent shavings and the verocity, heat and lenth or burn surprised (scared) me. (ok, I burned them after I removed the chips out of the drum )
The next lot of shavings I packed into onion bags. A very loosely woven bag about 10kg in size if it were to be filled with real onions or oranges. It does take some time to fill each bag but gives the opportunity to compress the shavings befor loading into the drum. Removing the chips from the drum is now very easy and makes handling and disposal very simple and spill free.
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