Axeman Anderson 260M Success.. Finally

Axeman Anderson 260M Success.. Finally

PostBy: LsFarm On: Mon Jan 14, 2008 6:02 am

I finally with a lot of help have exorcised the evil spirits and got my boiler burning coal properly.

I had started back in November with problems with the motor running the fan and auger, then I had problems with the ashgrate getting clogged with fine powdery-ash coal ash.

All along I was having a very significant amount of unburnt coal and partially burnt coal in my ashpan. I was going through large amounts of coal, and having to sift out the unburnt coal from the ash [I just couldn't throw it out :D ]. The recovered coal I burnt very easily and well in my underfeed stoker in 'Big Bertha'.

With several phone calls to Axeman Anderson, AHS, and coal boiler servicemen who service AA boilers, I slowly worked through several potential issues causing my huge amounts of unburnt coal in my ashpan.

Many, many AA and AHS 130 owners reported that they had zero issues with unburnt coal in their ash..

I spent many hours talking with forum member U235a4 who is the only other AA 260 owner on the forum. He too had had in the past lots of unburnt coal in his ash, as well as clinkers, temp overshoots, and many other problems. Zach tried his best to help me get the problem solved, and his help was right on target, now that I see what the actual problem was,

So... what was it?? Why did I have an ashpan full of 10-20% ash and the rest unburnt coal?? How is this possible when if I looked through the inspection port at the top of the fire, it appeared to be burning all the way across the full firepot/firetube??

Here's how I discovered what was happening. First, remember that the AA firechamber is a steel cylinder surrounded by water sitting 4" above a sliding 'grate', actually a drawer with steps or notches in the drawer bottom. The column of coal and the fire all rest on the ash grate or drawer bottom, There is a 4" gap between the grate bottom and the bottom lip of the firechamber.

I had what appeared to be a full fire, and had had this for several days, I was having the ashgrate 'ash' or move at a high rate to purge the firechamber of the unburnt coal, this was per the directions of Pete Axeman and U235a4. But after days of sifting through wheelbarrows of 80-90% coal in the ash pan, I had had enough...

I laid down on the floor, on my back and reached up and cleaned off 'exit end' of the ashgrate, I was pulling handfulls of unburnt and partially burnt coal off the grate and into the ashpan. I kept at this, expecting to start seeing red hot coals in the ash pan. But I had pulled a lot of coal out and was reaching in really far when I realized I had my had inside the fire chamber, and was still removeing unburnt coal. So I stuck my head inside the base and looke above the grate...

What I saw was that I had cleaned out a ring or cylinder of unburnt coal from the firechamber, and that in the center of the fire chamber was a column of red hot coal, like a tree trunk or the stem of a mushroom with an upper cap or top of burning coal. When the coal is hot it slightly adheres to itself, but the loose unburnt coal just fell out of the firechamber.

What I had was an insulating ring or cylinder of unburnt coal surrounding a central core or column of burning coal that was topped by a spread out cap of burning coal. Since all I could see was the top of the cap of burning coal that appeared to be the full diameter of the firechamber, I ahd no idea what the real situation was under the cap of burning coal.

What was happening to keep feeding this outer cylinder of unburnt/partially burnt coal was that each time the ashgrate 'ashed', it shaved some ash and unburnt coal off the bottom of the column of coal and fire. The whole column dropped an inch or so, and fresh coal fell down on top of the fire from the feedtube above the fire. The fire is cone shaped on the top, so the fresh coal rolled down the slope and stopped at the outer perimeter of the firechamber, up against the waterjacket. Here the fire was barely burning, the main heat was in the central core or column in the firechamber. But it appeared that the outer perimeter WAS burning, but it WAS NOT. The outer perimeter of fresh coal sometimes burnt a little, producing my large quantities of partially burnt coal, but a lot just slid down the wall of the firechamber to the lower, cooler area under the cap of burning coal.

Visualize a big mushroom, with a stem 11" in diameter, with a cap 14-15" diameter on top, with fresh coal being pourd over the top, and the fresh coal collecting around the stem of the mushroom insulating it from the surrounding waterjacket.

This is what I had in my firechamber. Pete Axemand and U235a4 both had told me to increase the amount of ashing to purge the excess unburnt but it wasn't working because of the constant feed of fresh coal from above.

I cleaned out as much unburnt as I could, burnt up my glove pretty bad, then got up off the floor, and from above using a poker pushed the fire down from the top, spreading the hot coals over the whole ashgrate bottom, some spilling out into the ash pan. I then dumped fresh coal on top, and started the fan in the boiler.

I turned up the thermostats in the house, and turned on the hot water, and increased the hot water feed to the shop floor, putting as large a BTU load as I could on the boiler. I manually ashed the boiler as needed to keep red coals on the ashgrate, not letting the anthrastat control the ashing at all. I needed to create the hottest, largest fire I had ever had. I had NEVER since the beginning of November really had a full fire in the fire chamber, It LOOKED like a full fire, but because I can only see the top of the fire throgh the inspection port, I was fooled into believing that the whole firechamber was the same as what I saw.

Why on the AA firechamber will the fire not travel sideways and down?? I don't know, the fire will travel sidewasy and down against the airflow in my underfeed stoker, but it didn't for over two months in the AA boiler. I had to force a full diameter fire.

Now that a full diameter fire is established, it is maintaining itself, and even seems to be still purging the last of the unburnt coal off the grate.

I am generating only about 1/4 the quantity of ash, and it is all well burnt coal, many small 'mini-clinkers' and the ocassional fist-sized clinker and some powder-ash as well. My coal consumption is a fraction of before, since now it is only burning the coal, not running it through the firechamber into the ashpan, mostly unburnt.

The reason that I couldn't get the unburnt ash purged by over-ashing as Pete Axeman and U235a4 had directed, is [I think] because I needed to remove the outer cylinder of unburnt /partially burnt coal from the around the central column of burning coal to allow it to collapse and cover the entire diameter of the firechamber.

When/if I have to start another fire in the boiler, I will take great pains to create a perimeter of fire right up against the outer diameter of the firechamber, and make sure the fire is well established full diameter before filling the firepot with coal. The fire in the AA firechamber cannot be trusted to migrate out and burn through the entire firechamber.

Fingers are tired, going to add a few more thoughts in the next post.

Greg L
LsFarm
 
Stoker Coal Boiler: Axeman Anderson 260
Hand Fed Coal Boiler: Self-built 'Big Bertha' SS Boiler
Baseburners & Antiques: Keystone 11, Art Garland

Re: Axeman Anderson 260M Success.. Finally

PostBy: LsFarm On: Mon Jan 14, 2008 6:14 am

So why did I have such a problem with the 260M when the AA and AHS 130 owners report no problems similar to mine?? I believe that it has to do with the diameter of the firechamber and the volume of coal in the 130 vs the 260 boilers.

The firechamber in the 130 boiler is 11" diameter, with the depth at 12" . This depth is measured from the feed tube at the top of the firechamber to the floor of the ashgrate/drawer.
The firechamber in the 260 boiler is 16" diameter, with the depth at 14". The ashgrate/drawer is 1" deeper, so the firetube is actually only 1" deeper but 5" larger diameter. This I think is the problem. The fire is so large in diameter, that to get natural migration of the fire to the full diameter of the firechamber would take over an hour of continous burning, and that just isn't possible in my instalation or in U235's instalation either.

The diameter of the fire in the 130 boilers is optimum from what the owners here report, nobody has had ANY of the issues I've had with unburnt coal in the ash. But the much larger diameter of the 260 boiler's fire is not optimum, both myself and U235 had to go to great efforts to get the fire to burn the full diameter. It takes some serious effort to force the fire to burn full diameter, the 130 boilers appear to burn full diameter automatically with no special techniques or efforts needed.
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before the full diameter fire, 90% still burnable, this much ash in 15 hours burn time.
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After the full diameter fire is established, Double the burn time, about half the ash, and all fully burnt ash.
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Greg L
LsFarm
 
Stoker Coal Boiler: Axeman Anderson 260
Hand Fed Coal Boiler: Self-built 'Big Bertha' SS Boiler
Baseburners & Antiques: Keystone 11, Art Garland

Re: Axeman Anderson 260M Success.. Finally

PostBy: coalstoves On: Mon Jan 14, 2008 6:53 am

Congrats
Night and day in the ashes to say the least, now do you think it will maintain a full fire or slowly revert to an underburn situation ?

More Draft maybe :?: somewhere between heat up the chimney waste or unburnt coal in the ash pan waste .
coalstoves
 
Stove/Furnace Make: Harman and Liberty
Stove/Furnace Model: Magnum and Victory 700

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Re: Axeman Anderson 260M Success.. Finally

PostBy: LsFarm On: Mon Jan 14, 2008 7:02 am

From talking with Pete Axeman, Zach [U235a4], the AA serviceman and Jeff at AHS, once the full fire is established it should continue. The possible causes of reverting back would be if a large clinker developed and had to be forced out, it could allow a slot to open up that fresh coal could fill. Or any other significant interuption of the normal running/ ashing actions.

After deaiing with this boiler for these last months, I sure hope it continues with a full burn. My frustration level meter was reaching the 'red-zone' for awhile. :D

Greg L.
LsFarm
 
Stoker Coal Boiler: Axeman Anderson 260
Hand Fed Coal Boiler: Self-built 'Big Bertha' SS Boiler
Baseburners & Antiques: Keystone 11, Art Garland

Re: Axeman Anderson 260M Success.. Finally

PostBy: lincolnmania On: Mon Jan 14, 2008 7:28 am

that new ash is much better! resembles the ash from our kenmore.....if i can get my efm and alaska to burn that nice...
sounds frustrating, i'm glad you found the problem......do you think the whole ring will stay lit?
lincolnmania
 
Hot Air Coal Stoker Furnace: efm af-150 1982
Hot Air Coal Stoker Stove: alaska kodiak stoker 1986
Hand Fed Coal Stove: warm morning 1980 kenmore

Re: Axeman Anderson 260M Success.. Finally

PostBy: Bob On: Mon Jan 14, 2008 6:19 pm

Greg--Thanks for a really informative discussion!

What I took away as the main point from your posts is that it is vitally important to start the fire correctly to get a good burn. After reading the posts I went back and reread the AHS instructions to see if this point was made directly or if the instructions seemed to be written with that point in mind. The manual I have was published in 2007 and covers AHS models up to and including the S1500.

The first thing I noted, which I had not internalized before, is a warning on the cover of the maual to never let the boiler water temperature exceed 200 degrees. I need to adjust my high temperature limit that is currently set for 205!

The AHS instructions for starting a fire include the following points:
1. Before starting a fire it is advantageous for the system and the load to be cold because this will allow the establishment of a good burn;
2. The grate switch should be turned off before starting a fire
3. Allow the boiler to run for 2-3 hours to allow all the coal in the pot to begin burning before turning the grate on.

My conclusion is that the instructions seem to include steps designed to get the entire pot burning.

Three questions--does the AA include a way to disable the grate for startup and did you disable the grate when you originally started the unit? If you disabled the grate, how long did you have it shut off?
Bob
 
Stoker Coal Boiler: AHS 130
Coal Size/Type: Pea/Anthracite

Re: Axeman Anderson 260M Success.. Finally

PostBy: Flyer5 On: Mon Jan 14, 2008 7:04 pm

Glad to hear you got it figured out . You went through a lot of frustrating times . Maybe you can place 3 or 4 mice in the burn pot when you have to relight it to help speed things up ,just a thought .It was also great to hear Pete Axeman was willing to help so much even on such an old unit . Dave
Flyer5
 
Stoker Coal Boiler: Leisure Line WL110
Hot Air Coal Stoker Stove: Leisure Line Pioneer

Re: Axeman Anderson 260M Success.. Finally

PostBy: Yanche On: Mon Jan 14, 2008 8:33 pm

My AHS S130 with the grate timer does have a switch to turn off the grate motor. It's also useful when removing the ash tub. Prevents ash falling on the concrete. Forgetting to turn the switch back will cause a problem. Once while filling coal hopper and removing ash I got interrupted by a phone call. I forgot to turn the grate switch back on and put the hopper lid on. The next morning coal in the bottom of the hopper was burning! In my opinion the grate off switch needs to turn on a blinking lite when it's in the off position. A simple modification that I've let to do!

I light my boiler with an Ox-Accy torch through the inspection port. It's easy to get a full area burn, just move the torch to what's still not burning. Really gets going when you turn on the cxygen!
Yanche
 
Stoker Coal Boiler: Alternate Heating Systems S-130
Coal Size/Type: Anthracite Pea

Re: Axeman Anderson 260M Success.. Finally

PostBy: LsFarm On: Mon Jan 14, 2008 9:08 pm

I have had my ashgrate/drawer out so many times, I can't remember how I started the fire the first two or three times.
You can slip the belt off the auger drive to stop the ashing action, or you could prop something under the handle or against the handle-stop to stop the ashing. I always stoped the ashing for at least 30 minutes because it takes that long to get a decent fire going.

What really confuses me about the fire burning in the center of the burn chamber, with a cylinder of unburnt coal around a central core of burning coal, is WHY doesn't the fire migrate to the unburnt coal?? On a handfed stove, if you have an area of the coal bed that is not burning, and you find the grate blocked, once the air gets to the coal, the fire will migrate to the unburnt coal. In an underfeed stoker, you build a fire on top of the coal in the burnpot, and once established the fire will burn down, against the airflow, and even into the auger screw and tube.. So what is keeping the fire in the center of the burn chamber, when the air comes in from the outer lower perimeter???? Just doesn't make sense to me, But hey it is what it is. I now know what I have to do to get a good fire going if/when I have to restart a fire. I'm hoping that I won't for the rest of the season.

I'll post an addtional photo in a bit.. I'm removing the ashpan after 48 hours of burning, this is what I was expecting all along, and FINALLY I have two full days of ash capacity in the ash tub. Maybe another whole day if I wanted to have some spillage..

Greg L

.
LsFarm
 
Stoker Coal Boiler: Axeman Anderson 260
Hand Fed Coal Boiler: Self-built 'Big Bertha' SS Boiler
Baseburners & Antiques: Keystone 11, Art Garland

Re: Axeman Anderson 260M Success.. Finally

PostBy: Wood'nCoal On: Mon Jan 14, 2008 9:25 pm

Is it possible on a forced draft boiler like the AA to actually have the air moving through the burn tube so fast that it actually keeps the coal fire from spreading?
The "core" of the lower portion of the coal in the burn tube is ignited, and the entire top of the coal is ignited. These are the areas where the surrounding coal has slowed down the air flow somewhat. The coal below the burning top and the "core" is acting to slow the flow of air, but enough velocity exists around the sides of the burning coal column to prevent the fire from spreading on it's own. In theory, the fire should spread to the non-burning coal below and around the burning coal, but the strong upward air flow is "pulling the fire back". From what I've read here the AA has quite a strong fan in it. Once you were able to manually get the entire firepot or tube ignited the flow of air was able to feed the entire coal fire, so it maintained the burn.
What do you think? I speak from absolutely no experience what so ever, just an idea.
Wood'nCoal
 
Stoker Coal Boiler: 1959 EFM 350
Hand Fed Coal Stove: Harman Magnafire Mark I
Coal Size/Type: Rice and Chestnut
Other Heating: Fisher Fireplace Insert

Re: Axeman Anderson 260M Success.. Finally

PostBy: coaledsweat On: Mon Jan 14, 2008 9:46 pm

Wood'nCoal wrote:From what I've read here the AA has quite a strong fan in it.


So I've heard, sort of like a B-52 has a few throttles. :roll:
coaledsweat
 
Stoker Coal Boiler: Axeman Anderson 260M
Coal Size/Type: Pea

Re: Axeman Anderson 260M Success.. Finally

PostBy: Yanche On: Mon Jan 14, 2008 10:46 pm

Let me contribute some measurements on my AHS 130. I have measured the over the fire draft when the combustion blower is running. It varies widely from one measurement to another. From 0.10 to over 0.25 inches H2O. I suspect it has something to do with the position of the ash grate or the amount of ash/coal in the fire pot at the time. I wish it were possible to easily measure the draft draw up through the ash pit. But it is not easy, too many leak paths. I've got the instruments to measure combustion efficiency but just haven't got around to it yet. In any event less suppose it's bad. What would I adjust? It seems to me the only thing I could adjust to affect combustion is blower speed. But the over the draft measurements indicates the airflow varies with something. So much that I don't understand. Anyone know how to computer model hot gas dynamic combustion flow? Any MATLAB experts here?
Yanche
 
Stoker Coal Boiler: Alternate Heating Systems S-130
Coal Size/Type: Anthracite Pea

Re: Axeman Anderson 260M Success.. Finally

PostBy: LsFarm On: Mon Jan 14, 2008 11:15 pm

I just removed the ashpan after it collected the ash from 48hours of burning. The pan is near full, but probably could go for another 12 hours without too much spill over..

I had a few larger clinkers in the ash, but all in all the ash looks very good, with very little partially burnt coal and no shiney fresh unburnt coal like I had before.

Greg L
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LsFarm
 
Stoker Coal Boiler: Axeman Anderson 260
Hand Fed Coal Boiler: Self-built 'Big Bertha' SS Boiler
Baseburners & Antiques: Keystone 11, Art Garland

Re: Axeman Anderson 260M Success.. Finally

PostBy: Bob On: Mon Jan 14, 2008 11:28 pm

Yanche, I can't help with modeling but perhaps one of the variables that causes draft to vary when the fan is running is variation in the size of the coal in the burn pot--the smaller the average size of the coal the lower the draft. Someone posted in another thread that there tends to be a natural migration of larger pieces of coal to the outside of a stack when coal is stacked from a chute above. If that observation is correct then it would seem that the size of the coal will not always be homogeneous even from the same delivery. The average size of of the coal at any time will depend on where in the stack the coal is taken from.

Greg, weren't you experimenting with using buckwheat at some point with the AA? Perhaps size of coal was a contributing factor to the way the coal burned in the AA. Also, if the burn is not complete throughout the burn pot it seems that the way to correct that situation would be to turn off the grate (disable ashing in the AA). This would be similar to the directions from AHS to not operate the grate for the first hours of operation after starting a fire. My recollection is that you reported that you increased ashing to try to correct the problem rather than decreasing ashing.
Bob
 
Stoker Coal Boiler: AHS 130
Coal Size/Type: Pea/Anthracite

Re: Axeman Anderson 260M Success.. Finally

PostBy: coaledsweat On: Mon Jan 14, 2008 11:45 pm

Let me get this straight, starting a 260M is like hitching a team of draft horses to a pulling sled? Can't wait till this baby pulls. :)
coaledsweat
 
Stoker Coal Boiler: Axeman Anderson 260M
Coal Size/Type: Pea

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