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Newspaper Stove and Wood chip/pellet stove
Newspaper Stove and Wood chip/pellet stove
Reedtb2 at cs.com Reedtb2 at cs.com
Thu Feb 8 17:54:55 EST 2001
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What a lovely description of a significant experiment that we can all build
on. What was the outer chimney diameter?
Richard seems to have solved the problem caused by the fact that each sheet
of burning paper makes a low density sheet of charcoal that pulls away from
the mass and prevents further reaction. I'll have to try it, but here are a
few comments I hope Richard and others will try.
1) Isopropyl alcohol is an excellent fire starter. It has a higher boiling
point than methanol or ethanol, so doesn't evaporate as fast. It has a
higher heat content but not enough to produce yellow flames like charcoal
lighter fluid (refined kerosene or fuel oil).
2) The fact that you have an 18 inch flame means that you have pyrolysed the
paper and converted char to producer gas, but don't have complete combustion.
See my gasifier garage heater stove see below. We are having a cold winter
here in Golden, so I work on this stove in my garage on Saturdays (while
listening to Click and Clack, the Car Guys).
3) One can buy perforated steel (or stainless steel) with millions of 1/16"
holes for this purpose, grates etc. It is sometimsometimes used to make
radiant heaters in restaurants etc. I bought a 4X 8 ft sheet a decade ago
for $100 and have found many uses for it. Beats drilling holes! The holes
might work better than your SS screen - or might not.
One call also buy stretched metal sheets with diamond shaped holes.
~~~~~
Being motivated by the cold winter, I have recently made a similar unit for
wood chips or pellets using a 1 foot length of 6 inch stove pipe containing a
6 in OD X 5 in ID riser sleeve. At the top I put a 5in to 4 inch reducer and
above the reducer a 2 foot length of pipe to provide draft. I drilled 2 rows
of 3/16 diameter holes and one row of 1/4 inch holes on the slope of the
reducer just before the chimney. I put a stove pipe cap with a movable flap
on the bottom to regulate the pyrolysis-gasification air.
I filled the unit with 360 g of wood chips and added 40 g of alcohol soaked
chips. I then threw in a match and put the burner-chimney on. The chips
burned about 15 minutes with 63 beautiful flamelets visible (with a metal
mirror) down the chimney.
I burned the stove in my garage with no flue vent, so presumably achieved
~100% heat efficiency. The chimney acts as a radiator and the radiant heat
could be felt several feet away. There was a moderate smell of wood
combustion in the garage - it has a peaked ceiling. The fuel burned at a
rate of ~20 g/min or ~20,000 Btu/hr. Pellets would of course burn much
longer.
The ratio of primary to secondary air is critical in maintaining clean
combustion. I don't at this level of development recommend burning without a
vent and improved heat exchanger or longer pipe. However, it may be possible
by insulating the combustion zone to get full combustion and use without a
vent for short periods.
This is a lot cheaper stove than the pellet stoves ($1,000 - $2,000), but not
as convenient, since it is a batch process. It makes ~20% charcoal, so when
the volatiles are gone it is important to increase air to burn it - or
extinguish it for later use.
I describe this in detail because heating is a major problem in many parts of
the world and could become so in the U.S. as the cost of propane and natural
gas rises. I hope many improvements will be made in this forum.
STOVERS:
The initial intent of this site was discussion of improved cooking stoves.
However, it seems to me that heating stoves are equally important. The above
gasifier-heater-stove is quite similar to the natural draft inverted
downdraft (top burning) cooking stove that I worked on from 1985-1998 and
that Ron Larson and I reported on at the Banff "Developments in
Thermochemical Biomass Conversion" conference in May, 1996.
In a message dated 2/8/01 8:58:34 AM Mountain Standard Time, rdboyt at yahoo.com
writes:
Subj:Newspaper Stove
Date:2/8/01 8:58:34 AM Mountain Standard Time
From: rdboyt at yahoo.com (Richard Boyt)
To: stoves at crest.org
Dear Wastepaper Stovers,
I very much enjoyed Dr. Reed's account of
experiences trying to burn or otherwise recycle
newspapers. I remember that when I delivered carefully
stacked and wrapped bundles of newspapers to the local
salvage center I saw them dumped into a semi trailer
along with great quantities of garbage and other trash
and then head off for the nearest landfill. I decided
to try a tightly rolled log of newsprint as fuel for a
stove. No attempts to adjust combustion air, roll
size, or compaction, caused anything but a few more
outer layers to burn, and that only at the price of
considerable smoke and an unsatisfactory thin layer of
black char before it self extinguished.
Remembering the feriosity with which I once saw a
standing hollow tree burn, and had having experienced
several scarry flue fires, I formed a hollow cylinder
of newspaper and stood it vertically inside a well
insulated section of stove pipe. I set it on a grate
to admit primary air and and lit it at the inside
bottom. It worked fine until the inside sheets began
to shrink and distort and eventually restrict the flow
of combustion air so completely that it soon flamed
out, smoked copiciously, and finally died out leaving
the bulk of the paper not even scorched. I found that
I could solve the shrink clogging problem by wrapping
the newsprint in multiple layers around a small open
cylinder of hardware cloth 2 1/2 in. diam. and 14 in.
long. It worked very well at first but the high
temperatures reached in this miniature reverberatory
furnace soon destroyed the iron mesh "breather tube".
A replacement tube of expanded stainless steel has now
stood up very well to many very hot firings.
Starting the inside of the paper roll to burn is
difficult but can be accomplished by coating the
inside layer of paper with a bit of cooking oil or by
dropping flaming strips of thin waxed cardboard down
from the top. I usually get smoke during the lighting
and initial flaming stage as the center cavity emits a
flaming torch about 18 inches high that at night
lights up the landscape. As the flame dies back, the
inside of the now charred chimney of charred paper
begins to glow as the char is converted to ash.
Looking down inside the cylinder you see a bright
orange column of glowing char/ash. Flowing, sometimes
rippling up the surface of this golden donut is a
faint nearly transparent pale blue/purple film .No
detectable smoke is given off though a good deal of
heat rises from the glowing tube. It has no odor, does
not sting the eyes, and though I have purposely
inhaled modest quantities of it I have detected no
hint of early carbon monoxide poisoning. Several times
I have brought the glowing stove inside to help heat
the kitchen where it left only a few small fragments
of fly ash.
Yet another surprise awaits, for after the stove has
cooled, when the now cold breather tube is carefully
removed it brings out with it a multiple of very thin
fragments of white translucent newspaper ash that even
as you watch, breaks away suspended on the slightest
breeze. Once, an unbroken quarter sheet of
diaphanousbreak up in the air. It would be most
difficult to weigh these filaments as they literally
float on air. Total conversion of char to ash is rare
but usually only a couple of palm sized pieces of
charred sheet remain.
It won't heat your home but it might make a useful
small batch-loaded space heater for a well ventilated
workshop. Hope this proves useful to someone,
Richard Boyt 20479 Panda, Neosho Mo 64850
rdboyt at yahoo.com
Dr. Thomas B. Reed, President, The Biomass Energy Foundation, 1810 Smith Rd.,
Golden, CO 80401
Email reedtb2 at cs.com; 303 278 0558 home; 303 278 0560 Fax
