Chimney maintenance - silly questions

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Digit
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Newbie Topic Starter

14 years ago

The other day I indulged in the annual ritual of sweeping the chimney and somehow this triggered a couple of questions about big industrial chimneys.

Assuming these chimneys were cleaned how was it done? Looking at photographs its obvious that some of the biggest chimneys possibly/probably had an access at the bottom of the vertical flue others however give no such indication. Even with access how do you clean a flue that might be anything upto 6 ft diameter and 75 ft or more high bearing in mind that the associated winding/pumping/mill engine would be working as close as possible to 24hrs/day, 365 days/yr. It seems a silly question but I can't get it out of my mind, and its starting to bug me.

Thinking back through all the various problems associated with mines/mills/canals and industry in general I cannot recall a single instance of a chimney fire, did they happen?

~~~ The future is not what it used to be ~~~

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JohnnearCfon
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14 years ago

That is not a silly question at all! It made me think of one of the chimneys I was looking at on Friday. It went up about 30 feet, then went virtually horizontal for about 15 feet before rising vertically for another 30 feet or so. We did actually discuss how good a draft it would have drawn, didn't think of the cleaning aspect!!

Peter Burgess
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14 years ago

At the Brockham Brickworks near Dorking, a shot-gun was discharged up the chimney. This is known because it was mentioned in an officially reported accident caused by someone mucking about with said firearm! I recall it was fatal. 😞

Digit
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14 years ago

"Peter Burgess" wrote:
At the Brockham Brickworks near Dorking, a shot-gun was discharged up the chimney. This is known because it was mentioned in an officially reported accident caused by someone mucking about with said firearm! I recall it was fatal. 😞

Interesting, considering the solidity of some of the adherent material which the brushes find in my tiny and lightly used domestic flue that must have been a very dodgy task even without someone mucking about!

~~~ The future is not what it used to be ~~~

grahami
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14 years ago

Perhaps given the diameter of the flues and the fierceness(?) of the draft, the deposits etc were not considered a problem?

Cheers

Grahami

The map is the territory - especially in chain scale.

plodger
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14 years ago

I was speaking to one of the lady volunteer attendants at the small museum in St.Agnes last week and she told me a story of her father-in-law who was a shot-firer in a tin mine for many years. He quite regularly cleaned domestic chimneys in the village with a small charge of powder that blew all the soot up through and out the top. She told me that all the kids loved it but not so the neighbours, especially if they had washing out that day. Maybe it could have been done on a grander scale for proper stacks? It would be worth everybody turning out to see that.

Ian H.

JohnnearCfon
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14 years ago

I must ask DylanW on here if he can do mine! 😉

Morlock
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14 years ago

I suspect that very little soot was deposited as most boiler operators would avoid black smoke by various stoking methods such as 'Coking'. This is the practice of applying fresh coal at the fire door end of the grate so that volatile products were consumed as they passed over the incandescent part of the fire.
Later mechanical chain grate stokers achieved this effect automatically.

Soot must have settled out on colder surfaces as most feedwater economisers had mechanical raking.

Edit: Chimney fires are always the result of un-burned carbon in the flue so selection of fuel grade and stoking methods were essential to obtain best efficiencies.

ttxela
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14 years ago

I think alot of modern industrial chimneys have statically charged plates to collect soot, these can then be taken out and cleaned or even I believe have the charge reversed to make the soot drop off :smartass:

No idea how they cleaned them in the past.

Morlock
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14 years ago

#10

"ttxela" wrote:
I think alot of modern industrial chimneys have statically charged plates to collect soot, these can then be taken out and cleaned or even I believe have the charge reversed to make the soot drop off :smartass:

No idea how they cleaned them in the past.

I think electrostatic precipitators are for fly ash not soot?

ttxela
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14 years ago

#11

"Morlock" wrote:

"ttxela" wrote:
I think alot of modern industrial chimneys have statically charged plates to collect soot, these can then be taken out and cleaned or even I believe have the charge reversed to make the soot drop off :smartass:

No idea how they cleaned them in the past.

I think electrostatic precipitators are for fly ash not soot?

You could well be right 😞

Digit
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Newbie Topic Starter

14 years ago

#12

ttxela and Morlock you've both made very good points but they relate to what are in effect 20th century boilers and not to the several preceeding generations of boilers and their chimneys.
Many paintings and photographs exist that show significant black smoke emission from big chimneys. Also I can remember when I stayed over at my grandfathers house in the 1950's the very obvious emissions from 'the dye works' just up the road. As an aside I can also remember my grandfathers neighbours grumbling about the loss of their jobs when 'the dye works' closed just before the clean air act came into force.

~~~ The future is not what it used to be ~~~

Morlock
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14 years ago

#13

I agree, old pics are very revealing of early inefficient practices.

I suspect there is a connection between the higher flue gas temperatures of older/less efficient plant and soot deposit build up?

Something along the lines of dew point and soot 'sticky index'.

Edit: Perhaps Grahams point on diameter and gas velocity explains a lot?

Digit
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Newbie Topic Starter

14 years ago

#14

"Morlock" wrote:
I agree, old pics are very revealing of early inefficient practices.

I suspect there is a connection between the higher flue gas temperatures of older/less efficient plant and soot deposit build up?

Something along the lines of dew point and soot 'sticky index'.

Edit: Perhaps Grahams point on diameter and gas velocity explains a lot?

I think the answer may lie in this direction. Its certainly the case that early pumping engines were renown for their ineffeciency.

~~~ The future is not what it used to be ~~~

Morlock
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14 years ago

#15

I've read a little about the recovery of Arsenic from flue deposits but got the impression that the flues were only cleaned for that purpose?

Sure someone will know the answer to that one. 🙂

derrickman
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14 years ago

#16

different question.

Arsenic was calcined from crushed ore in ground-level flues built for that purpose - the remains of such a set can be seen at Bottallack.

''the stopes soared beyond the range of our caplamps' - David Bick...... How times change .... oh, I don't know, I've still got a lamp like that.

Morlock
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14 years ago

#17

"derrickman" wrote:
different question.

Arsenic was calcined from crushed ore in ground-level flues built for that purpose - the remains of such a set can be seen at Bottallack.

Thanks. 🙂 This thread has jogged my memory about a local chimney/flue, 'Stac-y-Foel' at Cwmavon.

http://www.schoolnetglobal.com/finished_clean/10832367357548847.html

http://www.digitaldesk.org/resources/afanvalley/cwmafan.htm

:offtopic:

Thrutch
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14 years ago

#18

I have wondered about chimney cleaning too - and I regularly stoke the boilers at a pumping station (Leawood Pump - 50" bore x 9' stroke Beam Engine, two locomotive type boilers, eighty feet high chimney - but located in the bottom of a valley). As far as I know, the chimney has never been cleaned internally, or at last not over recent decades of restored use (outside of the chimney is regularly maintained). In a search for a reason for poor steaming of one of the boilers I found the flues surprisingly clean. Further examination will need more preparation and more of a struggle - I feel that there should be heavy soot deposits in the flues/base of the chimney/chimney but the signs so far are that there are not. More information when it becomes available.

Digit
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Newbie Topic Starter

14 years ago

#19

"Thrutch" wrote:
I have wondered about chimney cleaning too - and I regularly stoke the boilers at a pumping station (Leawood Pump - 50" bore x 9' stroke Beam Engine, two locomotive type boilers, eighty feet high chimney - but located in the bottom of a valley). As far as I know, the chimney has never been cleaned internally, or at last not over recent decades of restored use (outside of the chimney is regularly maintained). In a search for a reason for poor steaming of one of the boilers I found the flues surprisingly clean. Further examination will need more preparation and more of a struggle - I feel that there should be heavy soot deposits in the flues/base of the chimney/chimney but the signs so far are that there are not. More information when it becomes available.

Thanks for the posting, very interesting. I visited Leawood earlier this year, nice setup, keep up the good work

~~~ The future is not what it used to be ~~~

Morlock
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Newbie

14 years ago

#20

Over the years I've noticed that disused industrial chimneys always seem to have a mound of soot at the bottom. This may be related to weathering effects.

Is it possible that the dimensions of said chimneys prevent excessive soot build-up by gravitatioal effects, the soot being unable to support its own weight after a certain thickness?