Production of Pulverised Fuels0 pages

Product Fineness
The historic size distribution for solid fuel to be
fired in suspension is 75% < 75μm.
However, this is greatly influenced by the calorific
value of the fuel and by the specific application.
For example, the cement industry has used the
criteria that the residue at 90μm should not exceed
a value of half the volatile content. Thus, a coal

Technical Data
with a CV of 20% needs to be ground to
90% < 90μm whereas a lignite with more than
40% volatiles need only be 80% < 90μm. Dried
coffee grounds have 80% volatile content, so can
be coarsely milled. Conversely, petroleum coke
with 10% volatiles must be much finer to ensure
complete combustion.

System Turn-Down
The fineness of the product from the mill is largely
unaffected by the processing rate so, particularly

in direct firing applications, the feed rate can be
adjusted to demand at will.

2A

4A

6A

8A

11A

16A

17A

18A

20A

MOTOR SIZE (kW)

5.5

11

18.5

30

37

75

90

132

250

CAPACITY (kg/h)

100

300

700

900

1 350

2 500

3 500

5 000

10 000

The above capacities apply for a coal with a
Hardgrove Index of 55 and a pulverised product
with the following cumulative residues:

PARTICLE SIZE (μm)

500

250

150

90

75

RESIDUE (%)

0.05

0.5

5.0

20

25

Complete Engineered Solutions
Atritor can provide the following services to ensure complete customer satisfaction:
• Full process plant design using the very latest 3-D SolidWorks and AutoCAD software

Mill Capacity
Two factors determine the capacity of a mill; the
required fineness and the Hardgrove Grindability
Index (HGI) of the material. The latter is
determined by a standard test method and can
vary from 30 to 150 or more. The lower the
number, the more difficult the material is to grind.
Typical European coals vary between 45 and 65
but even this is significant – the capacity at 45HGI
is only 60% of the capacity with 65HGI.

ATRITOR SIZE

• Process control systems with custom programmed PLCs

Product fineness is equally significant – the
capacity at 90% < 90μm is 70% of that at
80% < 90μm.
So for optimum capacity and minimised specific
power, a high volatile material with a high
Hardgrove Index should be sought.

• Supply of all equipment for a complete process
• Full installation service
• Experienced engineers for commissioning and operator training
• Process guarantees
• After-sales services and spare parts supply

Other equipment in the Atritor range

Our Dryer-Pulverisers have nominal capacities
ranging from 100kg/h to over 10t/h, but these are
influenced by the two criteria described.

Power Consumption
The specific power consumption is typically 2025kWh/tonne of fuel processed but is influenced
by the criteria affecting capacity, as it is inversely
proportional. However, less than one third of the

fitted motor power is used to rotate the mill, so
specific power does not increase significantly at
lower operating rates.

Maintenance
The Dryer-Pulveriser is designed for rapid
replacement of worn grinding elements. The
casing is hinged, allowing quick access to the mill
internals. All wearing parts are produced in our
own foundry in an abrasion resistant high
chromium alloyed iron and are stocked in large
quantities.

The single most important criterion affecting the
operating life of wearing parts, and thus the
maintenance cost, is the ash content of the fuel. In
this context, petroleum coke, with its invariably
low ash, is preferable to coal but most cleaned
coals will have less than 10% ash.

Multirotor Cell Mills
Atritor Limited
PO Box 101
Edgwick Park Industrial Estate
Canal Road
Coventry
CV6 5RD
UNITED KINGDOM
Tel
Fax

+44 (0) 2476 662266
+44 (0) 2476 665751

Micronisers

Classifier Mills

Atritor Dryer-Pulverisers are built to the
rigorous standards of BS EN ISO 9001:2000

Opposed Jet Mills
Website
For more information about
the company, visit our website

www.atritor.com
and send us your enquiry.
Email

sales@atritor.com