chapter - 1 introduction - Meghalaya State Pollution Control Board

Hills Cement Co. Limited.
High efficiency classifiers can be used in both the raw materials mill
and in the finish-grinding mill.
4. Standard classifiers may have a low separation efficiency, which leads
to the recycling of fine particles, and results in to extra power use in
the grinding mill. In high-efficiency classifiers, the material stays longer
in the separator, leading to sharper separation, thus reducing over
grinding. Electricity savings through implementing high-efficiency
classifiers are estimated at 8% of the specific electricity use.
6.2. FUEL PREPARATIONS
1. Coal is the most widely used fuel in the cement industry. Fuels
preparation is most often performed onsite. Fuels preparation may
include crushing, grinding and drying of coal. Coal is shipped “wet” to
prevent dust formation and fire during transport. Passing hot gasses
through the mill combines the grinding and drying. Waste heat of the
kiln system (e.g. the clinker cooler) is used to dry the coal if needed.
6.3. CLINKER PRODUCTION – ALL KILNS
(i) Process Control & Management Systems – Kilns- Heat from the kiln
may be lost through non-optimal process conditions or process
management. Automated computer control systems may help to
optimize the combustion process and conditions. Improved process
control will also help to improve the product quality and grind ability,
e.g. reactivity and hardness of the produced clinker, which may lead to
more efficient clinker grinding.
(ii) Expert control systems do not use a modeled process to control
process conditions, but try to simulate the best human operator, using
information from various stages in the process.
(iii) An alternative to expert systems is model-predictive control using
dynamic models of the processes in the kiln. A model predictive
control system can reduce energy needs by 4%, while increasing
productivity and clinker quality.
(iv) Additional process control systems include the use of on-line
analyzers that permit operators to instantaneously determine the
chemical composition of raw materials being processed in the plant,
thereby allowing for immediate changes in the blend of raw materials.
(v) A uniform feed allows for steadier kiln operation, thereby saving
ultimately on fuel requirements.
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