[Gasification] Weight, power and temperature Tests

Thu Dec 22 16:36:59 CST 2011

Tom,

As the volatiles evolve through the char and burn at the surface of the fuel
particle isn't it likely that the surface of the char sees at least 750C
from flaming combustion and up to 1350 C if some of the charcoal burns? The
internal temperature would be owner of course. The result should be a
slightly oxidative char.  

Thanks

Tom  

From: gasification-bounces at lists.bioenergylists.org
[mailto:gasification-bounces at lists.bioenergylists.org] On Behalf Of Thomas
Reed
Sent: Thursday, December 22, 2011 2:17 PM
To: Tom Reed; Discussion of biomass pyrolysis and gasification; STOVES;
Chuck Stevenson
Subject: [Gasification] Weight, power and temperature Tests

Dear Gasers and Stovers

Someone asked recently how hot the TLUD stoves got during operation.  I made
a number of tests below on gasifying several fuels.  The highest temperature
I measured during the pyrolysis operation with the Cen-Tech IR pyrometers
was 190 C.  However, when the yellow flame disappeared and charcoal was
gasifying the temperature rose to 350C.  

MESQUITE, LIGNIN, AND PINE TLUD  PYROLYSIS

THE FOLLOWING FUELS WERE BURNED IN A 4" D X 6" TALL TLUD STOVE AND THE
WEIGHT CHANGE RECORDED. 

image.jpeg

image.jpeg

Note:  The tests were done on a scale weighing to 1/2 g and time recorded
every minute.  

Dry wood typically has an energy content of 21 kJ/g.  However in the TLUD
stove only the cellulose contributes is vaporized, approximately 16 kJ/g of
weight loss, while the lignin is carbonized to charcoal.  

MESQUITE

Mesquite is said to have a very high lignin content, compared to other
woods, 64%!

If lignin is the precursor of charcoal, mesquite should give a very high
yield of charcoal.

152 g of mesquite chips were placed in the Wanderer stove and ignited with
the propane torch.

Time.  Weight.     DW (weight change)

0.         152

1.         141.            11          Mesquite  Chunks too big, requires
lots of ignition with propane torch

2.         135.            14

3.         128.              7

4.         121.              7

5.          110.           11

6.           98.            12

7.            86.        .  12.          Highest Temperature with Cen-Tech
IR pyrometers 190 C.  

8.           72.            14 

9.            60.           12

10.          46.           14

11.          34.5.        11.5

12.          21.          13.5

13.            9.         12.       End of yellow flame,  put charcoal in
can and weighed

Yield:    38 g ==> 38/152= 25.0%

COMMENT - this is a High charcoal yield, but not enormous.  The pine chunks
below yielded 15% charcoal.  

<><><><> 

Same experiment with lignin chunks from a brown forest lignin log broken up
by hand.  Incredibly light.  Probably the first time anyone ever gasified
pure lignin - and maybe the last.  It is a very low density fuel, since all
the cellulose was eaten by microorganisms.

Time     wt.             dW

0.           54

1.           47.            7

2.           40.            7

3.           32.5.       7.5               Some soot in flame

4.           27.5.       5

4.5.      26.            1.5               Yellow out

Yield 6.5 g,  12%. 

I have long believed that it is the lignin that is the precursor to
charcoal.

This experiment suggeststhis is probably not true.

<><><><> 

Pine block - Wanderer

3/4 sq x1" pine blocks

0.      96.5.      dW

1.         89.          7.5 

2.        85.         4.0

3.        80.5.    4.5

4.        76           4.5.               Can maximum temperature 190C.  

5.         71.            5

6.         65.          6

7.          57.          8

8.         51.5.       5.5

9.          46.         6.5

10.        39.           7              Flame low

11.           31.5.       7.5          Flame much higher, end effect

12.         22.           9.5           big fire

13.         13.              9             All block surfaces on fire, but
centers still outgasing

14.         5.5.          7.5          Can temp 350 with Cen-Tech IR
pyrometers

15 g charcoal = 15.5%

Note: dry wood has a typical heat of combustion of  21 kJ/g, so complete
combustion would generate (21000/60) 350 Watts/Gm-min. 

However in the TLUD this is reduced to maybe 16 kJ/Gm-min or 270
Watts/g-min, because mostly cellulose and water are volatilized and the
remaining charcoal generates  26 kJ/g, or 433 W/g-min. 

So a burn rate of 12 g/min would yield a (270 X  12) 3.2 kW flame.  

Fuel bed 4"D  x 3" deep

I hope this information is useful, but needs digesting.

Tom Reed

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.bioenergylists.org/pipermail/gasification_lists.bioenergylists.org/attachments/20111222/ebc51845/attachment.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image001.jpg
Type: image/jpeg
Size: 49205 bytes
Desc: not available
URL: <http://lists.bioenergylists.org/pipermail/gasification_lists.bioenergylists.org/attachments/20111222/ebc51845/attachment.jpg>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image003.jpg
Type: image/jpeg
Size: 10254 bytes
Desc: not available
URL: <http://lists.bioenergylists.org/pipermail/gasification_lists.bioenergylists.org/attachments/20111222/ebc51845/attachment-0001.jpg>