On the flow through the towers, I know they state to go from top to bottom. But with compaction being a drawback, is it possible to flow bottom to top. I know with a flow of .15 GMP (1 6" tower), it's not going to make much of a difference, but just a thought.

Any SPECIFIC reason for the top to bottom?

My resin beds are both FRP purification tanks that reverse flow, very much like that of a regular canister type filter with liquid coming in at the head and dropping into the tank until it reaches a point where it gravitates up a center pipe and out the opposite side of the head.
You can get the idea by viewing this page. These are the same tanks I am using going into my second year now. There is no issue with compaction or channeling doing it this way. The tanks' tube has to be modified for biodiesel resin use though (see how it's done following my reactor link in my sig)

I also use an FRP tank like Legal, but I flow from bottom up. I send the fuel down the tube, it exits the tube inside the bottom of the tank and flows through the resin bed as the tank fills and then out the top. AFAIK I have had no problems with either channeling or compaction.

I made the tube upgrade that Legal came up with. The only problem I had was with the protective coating on the black pipe dissolving in the BD. I had to refilter that out as my BD turned nearly black. I would recommend sanding off the coating before letting it come in contact with your BD.

Legal,

Have you noticed any disintegration on your FRP tank heads? I just opened mine yesterday to make some changes and it is now in 5 pieces.

I have emailed a local vendor of these filters to see if I can get a replacement head. If not I think I have come up with a jerry rigged solution.

So far I have had no deterioration in the heads. I am actually waiting for another tank, a larger one, that I am planning on filling with wood chips, filtering at the outlet port and then lead/lag resin with final filter (as I am now doing anyway).
If you can't get another head you can try these guys.

HTH

quote:

Originally posted by Dane M. Stewart:
On the flow through the towers, I know they state to go from top to bottom. But with compaction being a drawback, is it possible to flow bottom to top. I know with a flow of .15 GMP (1 6" tower), it's not going to make much of a difference, but just a thought.

Any SPECIFIC reason for the top to bottom?

I can't see where there would be any difference at all with compaction. My concern is , How do you drain your tower? When you are done pumping would you not still have a tower full of product? Or am I missing smething?

When using resin, you always have a few gallons of fuel in your towers until you change out the resin. Then you drain out all the fuel. There have been reported by others that there are issues with compaction and channeling. The bottom up approach eliminates or minimizes the compaction problem, but some have reported issues with channeling using this method.

My towers are small enough that I can just shake them up a little every couple of weeks and the resin will settle back down, thus eliminating channeling issues.

Some resins are more prone to these problems than others.

Legal,

quote:

If you can't get another head you can try these guys.

Thanks for the lead. How in the world did you know about this company? Do you know if these heads will fit a 2-1/2 opening? I guess I can give them a call Monday and find out.

Thanks again.

Dane, you dont say what medium your using. You say compaction, so I take it you arent using resin. The normal flow is top to bottom and that is best for most things. I used bottom to top with wood shavings and it woked fine, but that was with most of the tower filled with them, and I reverted back to top inflow. I had compaction but there was still enough flow thru the tower.

quote:

Originally posted by john galt:

quote:

The normal flow is top to bottom and that is best for most things.

Please expand on why you believe that.

Resin is top to bottom.

By experience wood shavings is best in a top to bottom set up - having tried both as I have already said.

If the direction is bottom to top the biodiesel tracks thru resin, and also loosens shavings, reducing contact.

Please let us know why you might think the opposite.

Euro,

One of the things at Arbor Biofuels Company that we have been concerned about, when providing advice, on Up vs. Down flow is the glycerin adsorbitive properties of the resin.

Initially Purolite was highly recommending Botto-up flow since in water purification this is the most effecient flow path due to the natural redistribution of the beads by size that occurs as the bed is slightly billowed around with bottom-up flow (essentially the larger beads redistribute to the bottom of the bed where as the small beads gradually move to the upper portion of the bed)

This redistribution eventually allows for better "plug-flow" through the column.

However we aren't doing water purification so there are new dynamics involved and over the long run or at industrial levels of production, these new resin bed characteristics/factors start to show up.

Van Gerpen, who is currently performing extensive work with both gel and macroporous ion exchange resin's, recently said something like, the more we study what we think is happening, the more we realize there are more factors than was originally thought.

So as the resin adsorbs the glycerin and the bed begins to hold higher quantities, back flowing may unsettle the glycerin bed which forms on the bottom of the ion exchange bed due to its much higher weight than biodiesel.

This is particularly true in the case of the macroporous resin which doesn't experience the compaction issues. The macroporous resin actually uses this glycerin layer to engulf/trap soaps rather than exchange them and this is a benefit may be disturbed by back flowing.

Bottom Line - I feel bottom-up is the best configuration for gel-type resins and top-down is the best way to flow the macroporous resin.

GCG

GCG.

Very interesting post. I may switch mine over this weekend. Thanks.