Analytical Techniques - Biomass Gasification, Pyrolysis and Torrefaction - page 441

in proximate analysis is different from the carbon in ultimate analysis. In
proximate analysis, it does not include the carbon in the volatile matter and
is often referred to as the char yield after devolatilization.

13.1.2.1 Volatile Matter
For the determination of volatile matter, the fuel is heated to a standard tem-
perature and at a standard rate in a controlled environment. The applicable
ASTM standard for determination of volatile matter is E-872 for wood fuels
and D-3175-07 for coal and coke.
Standard E-872 specifies that 50 g of test sample be taken out of no less
than a 10 kg representative sample of biomass using the ASTM D-2013 sam-
ple reduction protocol. This sample is ground to less than 1 mm in size
through cutting or shearing, and 1 g is taken from it. The sample is put in a
covered crucible, so as to avoid contact with air, during devolatilization. The
covered crucible is placed in a furnace maintained at 950 20 C. The vola-

tiles released are detected by luminous flame observed from the outside. The
crucible is heated for 7 min. After 7 min, the crucible is taken out, cooled in
a desiccator, and weighed as soon as possible to determine the weight loss
due to devolatilization.
For nonsparking coal or coke, Standard D-3175-07 is used which, follows
a similar process except that it requires a 1.0 g sample ground to 250 micron
size (as per D-346 protocol). The rest of the procedure is the same as above.
For sparking samples, it should be slowly heated to 600 C in 6 min and then
heated at 950 C exactly for 6 min.

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13.1.2.2 Ash
The ash content of fuel is determined by ASTM test protocol D-1102 for
wood, E-1755-01 for other biomass, and D-3174 for coal.
Standard D-1102 specifies a 2.0 g sample of wood (sized below
475

m) dried in a standard condition and placed in a muffle furnace
with the lid of the crucible removed. The temperature of the furnace is
raised slowly to 580

μ

600 C to avoid flaming. When all

the carbon is

burnt, the sample is cooled and weighed. Standard E-1755-01 specifies

25 C. After 0.5 1.0 g of dried biomass to be heated for 3 h at 575 6

that the sample is cooled and weighed.
For coal or coke, standard D-3174-04 may be used. Here a 1.0 g sample
(pulverized below 250 m) is dried under standard conditions and heated to

450 500 C for the first 1 h and then to 700 750 C (950 C for coke) for the
second 1 h. The sample is heated for 2 h or longer at that temperature to
ensure that the carbon is completely burnt. It is then removed from the fur-
nace, cooled, and weighed.

μ