chapter - 1 introduction - Meghalaya State Pollution Control Board

Hills Cement Co. Limited.
Energy savings depend strongly on the specific energy consumption of the
dry process kiln to be converted as well as the number of preheaters to be
installed.
Installation or Upgrading of a Preheater to a Preheater/Precalciner
Kiln- An existing preheater kiln may be converted to a multi-stage
preheater precalciner kiln by adding a precalciner and, when possible an
extra preheater. The addition of a precalciner will generally increase the
capacity of the plant, while lowering the specific fuel consumption and
reducing thermal NOx emissions (due to lower combustion temperatures
in the pre-calciner). Cooler replacement may be necessary in order to
increase the cooling capacity for larger production volumes. Fuel savings
will depend strongly on the efficiency of the existing kiln and on the new
process parameters (e.g. degree of precalcination, cooler efficiency).
Older calciners can also be retrofitted for energy efficiency improvement
and NOx emission reduction.
Average savings of new calciners can be 0.34 MBtu/ton clinker.
Conversion of Long Dry Kilns to Preheater/Precalciner Kiln- If
economically feasible a long dry kiln can be upgraded to the current state
of the art multi-stage preheater/precalciner kiln. Energy savings are
estimated at 1.2 MBtu/ton clinker for the conversion. These savings reflect
the difference between the average dry kiln specific fuel consumption and
that of a modern preheater, pre-calciner kiln.
6.5. FINISH GRINDING
Process Control and Management – Grinding Mills- Control systems
for grinding operations are developed using the same approaches as for
kilns. The systems control the flow in the mill and classifiers, attaining a
stable and high quality product.
Similar results have been achieved with model predictive control (using
neural networks).
Advanced Grinding Concepts- The energy efficiency of ball mills for use
in finish grinding is relatively low, consuming up to 30-42 kWh/ton clinker
depending on the fineness of the cement. Several new mill concepts exist
that can significantly reduce power consumption in the finish mill to 20-30
kWh/ton clinker, including roller presses, roller mills, and roller presses
used for pre-grinding in combination with ball mills. Roller mills employ a
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