Page 72 - Dust Explosions in the Process Industries

Dust Explosions: An Overview 45

100
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m-

MELAMINE POLYMER nkPEAT (WIEMANNJ
(GLARNER) \\
COAL IGLARNERJ

(WIEMANNJ COALS-
(WIEMANN) +p

LYCOPOOIUM
(GLARNERI
n z
0
'0 20 50 100 200
INITIAL TEMPERATURE OF DUST CLOUD ["CI

Figure I .48 The influence of initial temperature of dust clouds on minimum explosible dust con-
centration in air at 7 bar (abs) (Data from Wiemann, 7987, determined in a 7 m3 closed vessel with
IO k) chemical igniter, and from Glarner, 7 983, determined in a20 liter closed vessel with IO k] igniter).

concentration in the range 30O-50O0C, much lower than the 1200-1300°C found for
hydrocarbongases. This indicates that the underlyingphysics and chemistry is more com-
plex for organic dusts than for hydrocarbon gases.
The influence of the initialtemperature of the dust cloud on the minimum electric spark
ignition energy is illustrated in Figure 1.49, using the data of Glamer (1984). For the
organic materials tested, a common point of convergence for the straight regression

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u
5 IO2
z
W
z0
L= 10
STARCH CELLU\
HERBICIDE
I 0.088 mi
10-21 I I I
'I0 50 100 500 1000
INITIAL TEMPERATURE OF DUST CLOUD I"C1

.iB9 The influence of the initial temperature of a dust cloud on the minimum electric spark
ignitior energy (From Garner, 7984).