Coalgun- Puff backs & Explosions

dchartt wrote:anyone having explosions while the fan is running and furnace is in the middle of a call for heat? This is when most of mine occur, I have recently lowered my ashing temp and raised operating temp and the explosions have minimized, 124 ashing 175 operating temp

120 ash, 160 low limit, testing out the hyst on 5 vs 10.

Are you letting the hooper empty completly?

I find that temp higher or lower doesnt affect booms only ashing, firepot burn depth, available combustion air, draft do.

130 degree ashing temp and 180 degree operating temp. Tiny port hole 1/3 open. Barometric damper set to open at 0.04". Running since October 14th on a blend of roughly 60% Blaschak pea and 40% Stockton pea. No puff-backs (so far).

Burn rate for the month of December (so far) is 1.57 lbs. per "degree day".
Average of 29.8 degree days per day for December (so far).
Coal consumption is 46.8 lbs. per day on avg. so far for this admittedly mild month, while heating the home and all of its DHW.

lsayre wrote:130 degree ashing temp and 180 degree operating temp. Tiny port hole 1/3 open. Barometric damper set to open at 0.04". Running since October 14th on a blend of roughly 60% Blaschak pea and 40% Stockton pea. No puff-backs (so far).

i find that the hole wont prevent puffbacks completely maybe just mask smaller ones.

Are you running your hooper full at all times?
What is your Hyst setting?
What do you get for draft with blower on?
How long are you're cycles.

Freddy wrote:I'm going to guess you made the same mistake I did when I first fired my Axeman Anderson. Internally it is identical to your AHS. If you started with an empty boiler, and loaded it with coal and lit it, you will have giant booms for 24 or 36 hours. I learned the old timers put in a five gallon pail of ash first, then loaded the coal on top of that ash. Wood ash....not so good, it doesn't allow any airflow through the ash like coal ash does.
Once you get ash established your booms will be a rare event, but if conditions are just right (just wrong?) you might have one now & then. A buddy of mine has an AHS. He has found that putting a paper clip on the view port door and keeping the hopper full helps a lot. The first two years he had a few booms, but this year either one or zero, I can't remember. The paperclip on the door lets some air leak in during burns and that interrupts the methane build up. Yes, every boom occurs just as that door is dropping open after the fan shuts off. I built an anti boom device that fingers the door open for 10 seconds each time the fan tries to shut off. That purges the boiler and prevents booms.

Freddy got any pics of this device?

ValterBorges wrote:Are you running your hooper full at all times?
What is your Hyst setting?
What do you get for draft with blower on?
How long are you're cycles.

I fill the hopper every other day.
10 degrees hysteresis on the ash grate temp
0.03 to a lot (baro damper open and generally doing a good job of trying to maintain 0.04)
Never measured cycles. What are they? I'm going t o guess that the boiler generally recovers and the fan shuts off roughly 7 to 10 minutes after it starts running.

lsayre wrote:

ValterBorges wrote:Are you running your hooper full at all times?
What is your Hyst setting?
What do you get for draft with blower on?
How long are you're cycles.

I fill the hopper every other day.
10 degrees hysteresis on the ash grate temp
0.03 to a lot (baro damper open and generally doing a good job of trying to maintain 0.04)
Never measured cycles. What are they? I'm going t o guess that the boiler generally recovers and the fan shuts off roughly 7 to 10 minutes after it starts running.

7 to 10 minutes, how often?
How low is the hooper when you fill it?

Can you take pictures around the base and youre flue?

You have the belt driven model?

ValterBorges wrote:
7 to 10 minutes, how often?
How low is the hopper when you fill it?

You have the belt driven model?

How often depends upon primarily the outside temperature, and also upon the amount of laundry, dish-washing, and showers going on for the day.
The most I have ever added at one time so far is 114 lbs. after two days of running.

Mine is the belt drive S130 model. UL Listed and ASME certified.

ValterBorges wrote:You think burning nut would be better more air?
or buckwheat less air?

or no effect?

where would you put the pipe?

I think burning buckwheat would cause more puff backs. Looking at the A-A Bureau of Mines report it says the following:

"The equipment was tested under regular house-service operating conditions. To use Buckwheat in the Anthratube it was found necessary, owing to its more compact fuel bed, to drill a 7/l6-inch-diameter hole in balance plate W (fig. 4), so that more air could be provided over the fire. Without this air, the CO in the products of combustion would frequently, during start-up periods, build up to some 13 percent or enough to create an explosive mixture. The mixture would ignite and cause a “bump” or small explosion."

To me this says the denser coal packing with buckwheat raised the production of CO. Apparently the critical percentage is around 13%. Other data in the report shows percentages around 12.5%. With this lower number there is no mention of puff backs. Interestingly it says during "start-up periods", not the end of ashing.

The CO measurements were made at the boiler breach. I've got an Orsat and can make these measurements. I'll have to dust it off and collect some data. If the difference between 12.5% (no problem) and 13.5% (problem) is all the margin there is, almost anything that would increase the air flow would likely help.

Here's a couple pics of my updated version. About the same as the prototype but with a more industrial solenoid. The only issue I have is that it jumps people when it engages if they've never seen it before....or often if they have! The solenoid slams with a loud clank each time it deploys. It doesn't bother me as it's not in the house. I have been surprised that the arm has not fatigued and broken. It's fairly light steel held with a couple rivets. I built that arm as the prototype figuring I'd make a real one when it broke. At this point it's a fun thing to see just how long a poor design will work! At this point it has certainly slammed open & dropped shut thousands of times and never missed a beat.

I'm not sure how a factory would make one for public use. Using my idea it needs to open very quickly. To make that happen quietly would be a real trick.

I'm curious how dchartt is having booms while it's running. I've never heard of anyone having that happen.

Freddy,
I have a simular solenoid for my combustion blower air shut off.You can hear the solenoid slaming while being upstairs,sometimes when standing next to the boiler and not paying any attention, it not only make you jump but can make your heart skip a beat. One good thing about the loud slam is I can hear how long the blower is running. Dennis

Freddy,
I have to commend you on your Ani-Boom Device. That's some vision

[quote="YancheI think burning buckwheat would cause more puff backs. Looking at the A-A Bureau of Mines report it says the following:

"The equipment was tested under regular house-service operating conditions. To use Buckwheat in the Anthratube it was found necessary, owing to its more compact fuel bed, to drill a 7/l6-inch-diameter hole in balance plate W (fig. 4), so that more air could be provided over the fire. Without this air, the CO in the products of combustion would frequently, during start-up periods, build up to some 13 percent or enough to create an explosive mixture. The mixture would ignite and cause a “bump” or small explosion."[/quote]

I have been burning buckwheat in my AA130 since 12/4/11. Fired it with a bucket of ash inplace. Fire is riding at the site tube level. I drilled a 5/8" hole in the flapper per AA instructions. No booms or puffbacks yet.

Coal was from Sherman and is very hard and shiny. Some of it splinters when it hits the fire leaving a small pile of coal chips on the site tube lip. Seems to have slightly more ash content than coal I have previously used in my K-6.

Freddy wrote:Here's a couple pics of my updated version. About the same as the prototype but with a more industrial solenoid. The only issue I have is that it jumps people when it engages if they've never seen it before....or often if they have! The solenoid slams with a loud clank each time it deploys. It doesn't bother me as it's not in the house. I have been surprised that the arm has not fatigued and broken. It's fairly light steel held with a couple rivets. I built that arm as the prototype figuring I'd make a real one when it broke. At this point it's a fun thing to see just how long a poor design will work! At this point it has certainly slammed open & dropped shut thousands of times and never missed a beat.

I'm not sure how a factory would make one for public use. Using my idea it needs to open very quickly. To make that happen quietly would be a real trick.

I'm curious how dchartt is having booms while it's running. I've never heard of anyone having that happen.

Very nice Freddy.

Im wondering if something like this could be retofitted to replace the door and open and close based on the fan.

http://electricdampers.com/retirementca ... 1-full.jpg
http://electricdampers.com/

In combination with a fast actuator.
http://www.siemens.com/press/en/pressre ... 105015.htm