Coalgun- Puff backs & Explosions

Re: Coalgun- Puff backs & Explosions

PostBy: dchartt On: Sun Jan 15, 2012 10:25 am

hope everything works out alright for you rychw, i recently just switched to a mix of nut and pea, and there is some big chunks of nut mixed in. I would say its probably a 60/40 mix, 60 pea 40 nut. I got a deal because it was left over, anyway, i have noticed while coal is being dumped on the fire it is a lot less at a time due to the larger chunks of nut mixed in, pea just isnt flooding the fire like it use to...havent had any puff backs and have also raised my ashing to 130. With burning buckwheat and sv set to 130 i had burps, now with burning the pea nut mix i havent had anything so far
dchartt
 
Stoker Coal Boiler: AHS 130
Hand Fed Coal Stove: Glacier Bay

Re: Coalgun- Puff backs & Explosions

PostBy: pete6500 On: Mon Jan 16, 2012 8:14 pm

Been a while since I've read the posts. I left a post in regard to me keeping my fire as high up as I can so the fire is about 2" below the funnel outlet. I burn buckwheat and my flapper is the old style with no hole. I also have the grate timer which I adjust in relation to outside temp to keep the fire high. during high demand in cold weather I very seldom have to adjust it to keep the fire where I want it. One thing I have to mention, when the blower turns off and the flapper opens, I can hear and see the blue coal gas burning a nice flame. The key here is to see the blue flames. If I don't, the coal gas is not being burned and can travel into the flue by natural draft then get ignited. BOOM!!!! It's been fine this year with no booms as long as I maintain my fire high and nice blue flames. I hope this may help thanks for listening.
pete6500
 
Stove/Furnace Model: AHS130

Re: Coalgun- Puff backs & Explosions

PostBy: rychw On: Wed Jan 18, 2012 6:12 pm

coaledsweat wrote:Look at the amp rating on the motor's data plate, it should be under 2 amps. Get a controller that meets or exceeds that rating.


My grate motor plate says it draws 1.4 amps. I picked up a ceiling fan control rated at 1.5 amps. I wanted a higher rating but that is all they carried. I am going to install the rotary switch tomorrow and see how the boiler reacts with the grate moving at a slower speed. Hopefully there will be less new coal allowed into the burn tube and less chance of booms. I'll keep you posted.
rychw
 
Stoker Coal Boiler: AHS 130
Coal Size/Type: Pea
Stove/Furnace Make: AHS
Stove/Furnace Model: 130

Re: Coalgun- Puff backs & Explosions

PostBy: dchartt On: Thu Jan 19, 2012 6:06 pm

wouldnt it just run twice as long due to temp taking longer to increase and in the end there will be same amount of coal put onto fire just at a slower rate?
dchartt
 
Stoker Coal Boiler: AHS 130
Hand Fed Coal Stove: Glacier Bay

Re: Coalgun- Puff backs & Explosions

PostBy: rychw On: Thu Jan 19, 2012 6:48 pm

dchartt wrote:wouldnt it just run twice as long due to temp taking longer to increase and in the end there will be same amount of coal put onto fire just at a slower rate?


The assumption is that the amount of coal added slower will prevent the fire from being smothered by too much fresh coal added to the tube. I have noticed that if I turn off the ash motor in the middle of dumping, the thermo sensor temperature rises anyway, just not as fast if the motor is running. This is a test like all the other things I've tried. Since AHS isn't trying to help us and solve the problem, we have to do it by trial and error. :mad:
rychw
 
Stoker Coal Boiler: AHS 130
Coal Size/Type: Pea
Stove/Furnace Make: AHS
Stove/Furnace Model: 130

Re: Coalgun- Puff backs & Explosions

PostBy: dchartt On: Thu Jan 19, 2012 7:13 pm

.
Last edited by dchartt on Thu Jan 19, 2012 7:15 pm, edited 1 time in total.
dchartt
 
Stoker Coal Boiler: AHS 130
Hand Fed Coal Stove: Glacier Bay

Re: Coalgun- Puff backs & Explosions

PostBy: dchartt On: Thu Jan 19, 2012 7:14 pm

rychw wrote: Since AHS isn't trying to help us and solve the problem, we have to do it by trial and error. :mad:



I hear ya on that one....keep us posted
dchartt
 
Stoker Coal Boiler: AHS 130
Hand Fed Coal Stove: Glacier Bay

Re: Coalgun- Puff backs & Explosions

PostBy: coaledsweat On: Thu Jan 19, 2012 8:11 pm

dchartt wrote:wouldnt it just run twice as long due to temp taking longer to increase and in the end there will be same amount of coal put onto fire just at a slower rate?

Yes, of course. But by adding the same amount of coal over twice the period of time, the gases will be dispersed slower reducing the risk of rising to an explosive quantity.
coaledsweat
 
Stoker Coal Boiler: Axeman Anderson 260M
Coal Size/Type: Pea

Re: Coalgun- Puff backs & Explosions

PostBy: Yanche On: Thu Jan 19, 2012 10:11 pm

My ideal control system for a stoker boiler would be:

1. Measure delivered BTU
2. Feed it replacement coal equivalent to that required to make up the delivered BTU.
3. Remove ash corresponding to the burnt coal that produced the delivered BTU.
4. Do it all slowly and continuously.

What do we have now.

For #1. A fixed set-point aquastat. Starting at the hi limit you wait until the low limit point is reached.

For #2. You start burning more coal by turning on the combustion blower. This feeds more coal in the column because ash occupies less space allowing the fire and the fresh coal to fall lower.

For #3. At some fixed but adjustable fixed time (ashing timer models) you start removing ash. This also has the effect of disturbing the coal fire and adding more coal. With thermo-ash models you begin ashing a some fixed but adjustable radiated ash temperature.

For #4. None of the above steps are smooth, but are abrupt events which have time constants much, much quicker that a content burning fire would like. The feeding of coal and ash remover are also disjointed.

It all begs for a modern control system.

What can we do with what we have?

1. Make the aquastat differential a minimum. This will get the combustion blower burning sooner, hopefully reducing how much the fire get disturbed because the blower cycles on and off more frequently.

2. Lower the ashing rate by lowering the grate motor speed. "rychw" is trying this.

I all this fails then what's left? Changing the concentration of coal gases so that an explosive mix doesn't exist, i.e. a purge of the boiler firebox. A control method is still to be developed.
Yanche
 
Stoker Coal Boiler: Alternate Heating Systems S-130
Coal Size/Type: Anthracite Pea

Re: Coalgun- Puff backs & Explosions

PostBy: Bob On: Fri Jan 20, 2012 1:57 pm

Yanche wrote:What can we do with what we have?

1. Make the aquastat differential a minimum. This will get the combustion blower burning sooner, hopefully reducing how much the fire get disturbed because the blower cycles on and off more frequently.

2. Lower the ashing rate by lowering the grate motor speed. "rychw" is trying this.

I all this fails then what's left? Changing the concentration of coal gases so that an explosive mix doesn't exist, i.e. a purge of the boiler firebox. A control method is still to be developed.


I would add one element to the above list:

3. Raise the level of the burning coal in the firebox so that the coal gas is always exposed to an ignition source. To put it another way continuously burn off the volatile gases rather than letting them accumulate.
Bob
 
Stoker Coal Boiler: AHS 130
Coal Size/Type: Pea/Anthracite

Re: Coalgun- Puff backs & Explosions

PostBy: rychw On: Tue Jan 24, 2012 6:09 pm

I intalled the ceiling fan switch today in circuit with the ash grate motor. I've set it at the middle setting since there are three speed options. I have had puffs these last two weeks, some small some quite big. I will monitor the function of the grate motor at the slower speed and hope the puffs are eliminated. I've noticed the there seems to be a correlation between the frequency of the puffs and the boiler running to reheat after domestic hot water call. That is interesting since the fire would not be as strong when reheating from hot water call as it would be from heat call. Again I'll keep everyone posted.
rychw
 
Stoker Coal Boiler: AHS 130
Coal Size/Type: Pea
Stove/Furnace Make: AHS
Stove/Furnace Model: 130

Re: Coalgun- Puff backs & Explosions

PostBy: dchartt On: Tue Jan 24, 2012 6:44 pm

:idea: :idea: :idea: thats very interesting, I dont have a DWH coil, havent had any puffs in awhile had a few here and there awhile ago but nothing consistent
dchartt
 
Stoker Coal Boiler: AHS 130
Hand Fed Coal Stove: Glacier Bay

Re: Coalgun- Puff backs & Explosions

PostBy: Freddy On: Tue Jan 31, 2012 4:31 pm

Good day. My buddy with the AHS130 is in his 4th year. This year he has had more puff backs than ever. The obvious reason is a change of coal. He is still using Kimmel Pea size, but it is a different truckload this year. Obviously it has different characteristics. The first 3 years he would have a subtle boom on rare occasion. This year he has been troubled with heftier puff backs on a regular basis. I'm writing now as he has finally made changes that have made a huge difference. Hopefully a total and forever difference.

Big change #1: He installed a draft inducer with a rheostat. He now has "dial a draft". He wired it so it only runs while the fan is running and maintains a draft of .04. That made a good change, but still he had some minor puff backs.

Big change #2: He finally figured out how to set the Fugi control. The factory found the manual & emailed it to me. Come to find out the control was locked. Attached is the Fugi user manual. On page 19 you'll find the Lock system. Even following the manual it's tricky to un lock it, but we finally got it and then changed the ash temps. Before the asher came on at 130 and shut off at 140. Now it comes on at 125 and shuts off at 130. If any of you have the Fugi control and have trouble let me know & I'll be glad to try & help. Basically he set it at a low of 120, a high of 150, a Hysteresis of 5 and then told it to shut off at 130. It's odd how the "150" remains in the equation, but that's how it likes it. The very last hing you do is tell it the temp you want it to shut off at. His asher is allowed to run whenever it wants. I understand some people have wired it so the asher only runs while the fan is running. If he ever has another boom, this will be changed.

Change #3. He added a thick paper-clip to the bottom of the flapper door.

At this point he has been boom free for four days. Hopefully his issues are a thing of the past & hopefully this info can help others.
Attachments
Fugi 3 Manual_409c.pdf
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Freddy
 
Stoker Coal Boiler: Axeman Anderson 130 (pea)
Hot Air Coal Stoker Stove: Reading piece o' junk in the barn (rice)
Coal Size/Type: Pea size, Superior, deep mined

Re: Coalgun- Puff backs & Explosions

PostBy: McGiever On: Wed Feb 01, 2012 1:50 pm

You fellows running the Fuji Controllers may find this helpful, it outlines the steps for programming, although it is for a Kiln Oven application, the steps for programming should still apply.

Let us all know if this is of any help.

[The extension doc has been deactivated and can no longer be displayed.]



@ Freddy, What was the outlined steps for unlocking the Fuji, could you write it up in similar format as like I added? What year model S130 is you friends? Wondering what years the Fuji was standard. And when the Dwyer/Love Controller replaced it?

I should think your friend will see great improvements. Lowering the ashing temps will move the fire (hot coals) higher, which is better for when fresh coal is dump in on top. When it is a lower fire, it has so much more fresh coal that produce so much more gases that need to be burned or else! :!:
A proper draft goes a long ways towards keeping gases burned off too.

My belief is, if one has "puffbacks" they must get the fire(hot coals) raised higher in their firepot.

What the digital display reads on the controller may not match the owners manual or even what other AHS owners settings are...keep adjusting lower to get the fire higher and the problem will be gone.

Here is a picture of where I have my Paper Binder Clip:
Notice blue gases are ignited before being drafted away. This photo was taken immediately after blower had shut off.

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Paper Binder Clip And High Fire Position
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McGiever
 
Stoker Coal Boiler: AXEMAN-ANDERSON 130 "1959"
Hot Air Coal Stoker Stove: HARMAN MAGNUM
Hand Fed Coal Stove: RADIANT HOME AIR BLAST
Baseburners & Antiques: OUR GLENWOOD 111 BASEBURNER "1908"
Coal Size/Type: PEA / ANTHRACITE, NUT-STOVE / ANTHRACITE
Other Heating: Ground Source Heat Pump
Stove/Furnace Make: Hydro Heat /Mega Tek

Re: Coalgun- Puff backs & Explosions

PostBy: Freddy On: Wed Feb 01, 2012 4:10 pm

McGiever wrote:could you write it up in similar format as like I added? What year model S130 is you friends? Wondering what years the Fuji was standard.


No need to try & rewrite it, page 19 of that PDF is a show & tell of how the lock works. Charlie's (My buddy) AHS 130 was purchased new in the Fall of 2008. If I remember, the factory said the Fugi was used for about 2 years.

For sure the changes we made brought the fire higher in the burn chamber. It used to be it was rare to see orange when looking in the view port. Now it's orange most all the time.
Freddy
 
Stoker Coal Boiler: Axeman Anderson 130 (pea)
Hot Air Coal Stoker Stove: Reading piece o' junk in the barn (rice)
Coal Size/Type: Pea size, Superior, deep mined