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| CEMENT
INDUSTRY |
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Other energy efficiency aspects
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The
other miscellaneous energy efficiency aspects,
which need to be taken care in the design stage,
are listed below
- The bag filters & de-dusting fans distributed
over the entire plant consume about 2 -3 %
of the over-all energy consumption. These
fans should be designed, based on the individual
user requirement and not from the point of
standardisation. The typical de-dusting air
requirements for different applications are
given below
Equipment De-dusting air quantity
Hammer crusher 100m3/hour/ton
Bucket elevators 1800m3/hour/m2 of BE cross
section
Pneumatic conveyor Conveying air + 50 %
Air slides Air supplied + 20 %
Cement packers 2000 m3/hour/spout
Bins section 4000 m3/hour/m2 of bin cross
- It is always better to have individual
dedicated package compressor, for the individual
bag-filters. This will help avoid long compressed
air lines & minimise leakages. The small
compressors are 'ON/OFF' types, while the
bigger compressors are controlled by loading/unloading
machanism. Hence, the installation of smaller
dedicated compressors for individual bag filters,
will ensure energy efficiency. We recommend
installing separate small package compressors
for individual bag filters.
- The rating of motors should be done, such
that, the motor operates at higher loading
factor, say more than 80 % during the normal
operation. The safety margins of the motors,
should be discussed with supplier in detail,
to avoid under loading of the motor during
operation. Wherever the starting load decides
the motor capacity, it is recommended to install
soft starters, to take care of the starting
torque.
- The transmission of power from the prime
mover to the driven equipment should be 'Direct'
as far as possible. Wherever a belt drive
is required, it is recommended to install
a flat belt drive.
- Installation of LED's for indication lamps.
Presently filament lamps are being used for
the indication purposes. The LED lamps can
be installed in place of filament lamps, with
reduced energy consumption & longer life.
Electrical systems
Lighting system
In a cement plant, lighting consumes between 1
- 1.5 units / ton of cement, depending on the
extent of lighting. There is a good potential
to save energy in lighting system by optimising
the system voltage. This can be achieved by having
a separate line and transformer, so that the lighting
voltage can be regulated and maintained at about
210 V. At the design stage itself, a cement plant
should install only energy efficient lighting
as below
- HPSV lights for plant and outdoor lighting
- Fluorescent tube lights with electronic chokes
and compact fluorescent lamps ( CFL ) for inside
lighting
Electrical distribution
The electrical distribution should have an auto
PF control system and an 'on-load' tap changing
facility for the main transformer. The auto PF
control system will aid in maintaining high PF
on a consistent basis. This will enable consistent
PF and better demand management of the plant.
The 'on-load' tap changing facility of the main
transformer, enables maintenance of the optimum
voltage as required by the system. The optimum
voltage helps in operating the motors at higher
efficiency.
Generators
The oil fired generators are also being installed
to supply power to the plant during power failures.
The generators should have the facility of operating
in parallel with the grid. The facility should
be such that, the kiln continues to operate, even
when the grid power fails.
These generators should have the following facilities
- Operation with multiple fuels
- Waste heat recovery systems, which can be used
for generator oil heating.
The waste heat can also be used for meeting the
plant A/C load by installing a vapor absorption
refrigeration system.
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