Bridging

 
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Lightning
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Post by Lightning » Sat. Nov. 26, 2016 10:40 am

Sunny Boy wrote:
corey wrote:I didn't know anthracite bridges. Learn something new each day
Not in all anthracite stoves, Corey.

Alot depends on firepot size and temp the firebed is run at. My range has a long, but narrow firebox. Running it hotter during the day, mine will sometimes bridge - especially if I let it run longer before refueling. But, dampered-down and idling overnight, it doesn't bridge at all.

Paul
Also, bridging with bit is different than anthracite. Bit tends to melt into a big solid mass bridging that way. Anthracite doesn't do that, the top layer of coal forms an arch spanning from one side to the other held together by gravity. It's unstable and doesn't take much to make it fall. A bit bridge takes a beating to break it up. Some bit coals bridge differently than others.


 
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Post by Sunny Boy » Sat. Nov. 26, 2016 10:46 am

Lightning wrote:
Sunny Boy wrote:
Alot depends on firepot size and temp the firebed is run at. My range has a long, but narrow firebox. Running it hotter during the day, mine will sometimes bridge - especially if I let it run longer before refueling. But, dampered-down and idling overnight, it doesn't bridge at all.

Paul
Also, bridging with bit is different than anthracite. Bit tends to melt into a big solid mass bridging that way. Anthracite doesn't do that, the top layer of coal forms an arch spanning from one side to the other held together by gravity. It's unstable and doesn't take much to make it fall. A bit bridge takes a beating to break it up. Some bit coals bridge differently than others.
If run hot enough, anthracite does get to a point where it's a plastic-like, sticky stage. You can feel the difference in how it gets "mushy" when working a poker down though the top of a really hot firebed. That's one of the reasons some say to never poke a hot fire from the top, or it helps form bigger clinkers. I've found that to be true going by the size of clinkers I've dug out after shutting down the range.

Paul

 
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Post by joeq » Sat. Nov. 26, 2016 10:51 am

I'm assuming clinkers are what causes bridging. And wouldn't the characteristics of a round pot be more suitable for a bridge, than a rectangular pot? And on the clinker subject, does anyone know what causes clinkers? Is it poor coal quality, or just a specific trait from the temps the coal is subjected to?

 
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Post by Sunny Boy » Sat. Nov. 26, 2016 11:28 am

joeq wrote:I'm assuming clinkers are what causes bridging. And wouldn't the characteristics of a round pot be more suitable for a bridge, than a rectangular pot? And on the clinker subject, does anyone know what causes clinkers? Is it poor coal quality, or just a specific trait from the temps the coal is subjected to?
I think it can be a bit (no pun intended) of both, Joe.

Paul

 
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Post by Lightning » Sat. Nov. 26, 2016 11:37 am

Here's a thread I started about clinkers a few years ago Joe ;)

Clinker Removal? Time to Go Fishing!

It usually happens with red ash coal as it has an abundance of iron in it. If run hot enough the ash fuses together in clumps and the clumps grow over time during hot fires.

The clinkers just end up taking up space in the fuel bed taking place of healthy burning coal. Once there is an abundance of clinkers you'll loose burn time and heat output.

 
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Post by freetown fred » Sat. Nov. 26, 2016 11:44 am

Never had a clinker nor bridged anything in the old HITZER---using BLASCHAK bulk from the git-go---I'm feelin left out!!!!!!!!!!!!!! ;)
Last edited by freetown fred on Sat. Nov. 26, 2016 11:49 am, edited 1 time in total.

 
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Post by tcalo » Sat. Nov. 26, 2016 11:47 am

joeq wrote:And on the clinker subject, does anyone know what causes clinkers?
Clinkers, or slag, are made up of elements and minerals found in coal which are non-combustible. When burnt, they melt and fuse together, forming lumpy ashes. I believe this happens at a certain temperature called "ash fusion temp". The point at which ash becomes molten and fuses together. I'm not sure of the exact temp, but I know it's hot.
lobsterman wrote:I think the ash-bound fire pot sneaks up on us over a number of days when little by little we don't quite clear it enough.
I had trouble clearing all the ash when running my Chubby. Every few days the stove got ash bound quite bad and I really had to work it to get everything cleared. My Glenwood is a gem to tend. The draw center grate is a blessing. Sure I still get clinkers, but they fall through the draw center with ease. Due to the great bridging my stove does I get 90% of the ash cleared with the grate pulled out. A quick shake or two with the grate in and back in business. I didn't get bridging with the Chubby, probably due to the wider pot. I do lose more good coal using the draw center grate versus the Chubby grate. I had nothing but fine powder with the Chubby, but clearing clinkers was a pita. Clearing the G109 is a dream!


 
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Post by joeq » Sat. Nov. 26, 2016 11:51 am

Fred, consider yourself lucky. I'll send you a few to install, if you want to participate. :lol:
Thanks for the link Lee. I'll check it out later, as I'm off on errands right now. Gutta chip away at that "ta-do" list, don't-cha-know?
And Tom, is there a remedy to minimizing clinkers?

 
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Post by Sunny Boy » Sat. Nov. 26, 2016 12:03 pm

Before I replaced the warped triangular grates in my range, heat output would slowly drop off over the course of a few weeks. No matter how much I was shaking, or poking up through the grates, without being able to turn the grates, clinkers built up in the bottom, getting larger and harder with time until the firebox could only hold about half as much burning coal.

Some of the clinkers were the size of a baseball and rather meteor like. :shock:

With the new grates I was able to at least once a day rotate them to grind/dump the clinkers while they are still in a flaky/crumbly state. And, no more once a month having to shut-down to get rid of clinkers so that I can get the heat output back up. :)

Paul

 
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Post by joeq » Sat. Nov. 26, 2016 12:18 pm

So Paul, are you saying your old grates were so badly distorted, they wouldn't allow full movement or rotation for grinding the clinkers?

 
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Post by lobsterman » Sat. Nov. 26, 2016 12:20 pm


Ready for the big poke.
Poke her long and hard.

 
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Post by corey » Sat. Nov. 26, 2016 2:18 pm

Sunny Boy wrote:
corey wrote:I didn't know anthracite bridges. Learn something new each day
Not in all anthracite stoves, Corey.

Alot depends on firepot size and temp the firebed is run at. My range has a long, but narrow firebox. Running it hotter during the day, mine will sometimes bridge - especially if I let it run longer before refueling. But, dampered-down and idling overnight, it doesn't bridge at all.

Paul
So it stove design and firebed temp. Soundso like a lot of variables here.

 
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Post by lobsterman » Sat. Nov. 26, 2016 2:42 pm

And we are mixing two things here. Although clinkers can create a serious bridge, one can also be formed without them. I seem not to burn hot enough to get serious clinkers and I am burning red ash. I get bridging, however, over soft ash.

 
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Post by corey » Sat. Nov. 26, 2016 3:15 pm

This KY bit it stays in lump form no swelling. Not had a clinker jam the grates yet.

 
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Post by Sunny Boy » Sat. Nov. 26, 2016 3:34 pm

joeq wrote:So Paul, are you saying your old grates were so badly distorted, they wouldn't allow full movement or rotation for grinding the clinkers?
Correct, Joe.

They were warped, (bowed) so badly that that they hit the sides of the grate frame, or each other. They could only be rotated the slight amount as when just shaking ash. And poking up through the grates only broke up what was right over the gaps. Any clinkers that could not be reached on top of the grate bars just got tougher/harder and then grew larger because as they did, the poker could only push aside, not brake them up.

Paul


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