CPT International 02/2015

Figure 1: Flow diagram of the petcoke feeding plant supplied by Dako GmbH
Figure 2: Manifold at the furnace
to a constantly high carbon content
above 90 %.
In a downstream combined drying
and grinding process, the crude petcoke
is processed into pulverized petcoke.
In order to ensure reliable conveying
of the pulverized material it is
necessary to achieve a residual moisture
content below 1%. Combined
with a low ash content, the pulverized
petcoke supplied by Dako Coal
GmbH, based in Essen, Germany, features
a guaranteed calorific value above
34,000 kJ/kg, making it the commercially
available solid fuel with the
highest calorific value.
Compared to other pulverized fuels,
especially pulverized lignite, pulverized
petcoke is a low-reactivity fuel
(ignition temperature at around
700 °C) due to its low content of volatile
matter (< 10 %). In order to be able
to fulfill the igniting and combustion
requirements for use in industrial furnaces,
the petcoke must be ground in
a sophisticated process down to a fineness
of R 0.09 mm < 6 %.
The soft structure of the crude petcoke
produced in Germany (HGI > 70)
gives the powder properties similar to
graphite. Thanks to these properties, it
is ideally suited for quasi abrasion-free
Runner iron temp. in °C
1510
1505
1500
1495
1485
1480
pneumatic conveying. In spite of its
large surface area, pulverized petcoke
can be considered as non-explosive, in
contrast to other solid fuels in powder
form. When a plant is designed, the
risk assessment generally reveals that
there is no need to implement any constructional
(tertiary) explosion protection
measures. The safety-related plant
engineering requirements are limited
to measures that avoid the occurrence
of ignition sources (primary and secondary
measures).
R-Temp.
PET kg/h
1475
08:38 08:45 08:52 09:00 09:07 09:14 09:21
Time
Figure 3: Effect of petcoke rate on runner iron temperature
260
250
240
230
220
210
190
Petcoke feeding rate in kg/h
Petcoke in a cupola – a longterm
test
Only a long-term test was considered
to be suitable to provide reliable and
conservative information about the
use of petcoke in cupola furnaces.
Linde conducted such a test together
with Dako Coal GmbH. As early as in
2012, at the International Cupola Day
in Dresden, Germany, Linde and Dako
presented their first petcoke project: At
the Weilbach plant of Linde Material
Handling GmbH, they tested the fuel
Casting Plant & Technology 2/2015 33