Smoke in Coal Bin

The auger flights are very worn and rounded. Certainly not sharp.

The auger pipe holes are up and the pipe is fully seated. I don't know if the holes are aligned properly. However, almost every time I remove the pipe to work on the pot they are clogged with coal fines. I suspect the wet coal dries in the holes.

I will buy a new upper auger pipe, and both worm sections to see if this is helps.

How far from the edge of the pipe/pot do the holes need to be and what are the diameter of the holes? I don't recall if I made this pipe out of sch 40 or purchased it from EFM. It looks factory made.

Dave

If the auger holes are plugged with fines, that is most likely your problem. All of your problems go back to the coal being wet, and perhaps having a large amount of fines. I doubt there is anything wrong with the bin auger...unless it is bent. The pot auger might be toast, especially if you ran it with a worn out pot bushing.

The holes should be 1" from the end of the pipe. I think they are 3/16", and there should be seven of them...directly across from the notch for the index pin. Here is a picture, courtesy of Matthew Direnzo.

The auger flights are supposed to be round or squared off. It's when they are sharp that they are bad and that is usually the flights at the bottom of the pot opening. Either way, they are not causing your smoke issue. If you had one of the old Bacarrach draft meters, you could probably insert the probe into the open ended pipe and seal it with, possibly sand, and get a draft reading there. Never did it, but it might work.

Thanks Rob. I'll pull the pipe tonight, and double check the spacing and holes. I'm drying the coal for a few days before I place it in the DF520 so this has helped. I'll buy new auger anyway. I drove home at lunch today to switch over to oil since wife called about the smell in the house.

You will have never ending problems if you keep burning overly wet coal, especially if the rice contains a lot of fines/dust.

Since this seems to be a common problem people experience with these stokers, is there any reason there isn't a small tube from the blower applying positive pressure to the auger tube a foot or so before the retort? This is standard on all bituminous stokers and it prevents just these problems.

My thoughts are that anthracite is generally, under good conditions, less likely to off-gas prior to arriving at the point of combustion in the retort. However, under less than ideal conditions (probably why there were holes drilled in many of these augers a few inches before they enter the retort) such as moist coal, poor coal, coal too large etc. there will be gasses migrating down the auger tube. Because bituminous coal is more likely to off-gas under most conditions (as well as generally being a larger size that doesn't "seal" as well) prior to entering the exact zone of intended combustion, all bituminous stokers head off this problem by a simple and very effective solution - using a small tube from the combustion blower to the auger tube about a foot or so prior to the stoker retort.

It seems as if this problem is both somewhat common and very unpleasant/potentially dangerous in its result, thus a complete and yet still very simple solution such as that used by bit stoker mfg'rs would be the ticket here to keep this from being a chronic customer complaint.

What size is said tube? It would be easy enough to drill a hole in the air chamber and auger pipe, then run a piece of soft copper or whatever.

I disassembled the upper tube and auger, and all the 7 holes were completely caked with dried fines. Compressed air directly on the holes would not open them so I had to pick them open. The holes were 1" center from the edge as the picture showed, and there were 7 of them mounted up.

It would be great to try the tube idea. I'll volunteer to try it!

I put everything back together, and will start it up again. Unfortunately, I have no way to completely dry tons of coal. I'll drain bags in xmas tree bin or outside once warmer, and then dump coal into another staging bin. Then shove from staging bin to coal bin once dryer. 3 stage setup!

Dave

Rob,

Would buck size coal be better from bags?

Dave

They're typically about 3/4" dia.

Buck is a double edged sword. It usually has less fines and the water drains out easier, but it is more likely to allow gasses to go back through the auger. If you install a tube like Berlin suggests, buck might be fine.

I burn buck with good results, but if I let the drum get low on coal it starts to stink.

I can honestly say that all calls to efm about smoke were from owners who used a short(ened) pipe and a barrel. If there was a call from anybody who used the designed long pipe set, a smoke problem was from some glaring reason like a bad chimney or blocked pipes, among others, and was quickly resolved.

One thing I thought of was this: Is your pipe coupler sealed at each end with cement and are the pipes tight together inside?

I am going to send you a PM with my number and if you don't get this issue fixed, we are going to go step by step to find out what's wrong. You will need a reliable draft meter to measure draft before the damper and at the front door.

I think the clogged holes in the upper pipe caused the smoke issue. Been running for 2 hours now, and no smoke after cleaning the holes. Of course, I cleaned out the pot again too, but didn't find any of the holes in the plate clogged.

Anyway to clean out these holes without taking the pipe out? Its a lot of work, but I can do it in an hour now.

Dave

Why can't you setup a small bin to let the coal dry?

Rob,

I had a bin to let the water drain out of the bags (just shy of 1 gallon per bag), but i'm going to now dump the coal out of the bags after I let them sit for a day into a another bin to let it dry more. Then shovel into the coal bin. Started this tonight. I had to let the water out of the bags some how in a contained area. Otherwise, its a mess. When its warmer, I'll let the bags drain more outside. Just sitting them upright, and cutting corners lets a lot of water out. They are all frozen now.

I did try a different pallet of coal, and its much dryer so this should help. I'll keep cleaning out those 7 air holes.

Dave