Good day.
Is ther anyone who uses rice husk in their cement manufacture i.e. as a pozzolan or burning it in the kiln for energy?
If so can you send me your contact please? If not you can send me an e-mail at stephenb@tcl.co.tt
Thank you.
Raj Sahu
Please find a case study of one of the plant
Usage of Cheaper Fuels for Calciner Firing
Background
The Kiln and the Calciner are major consumers of fuel in a Cement plant. The
fuel cost amounts to nearly 20 % of the manufacturing cost. The increasing cost
of fuel and the competition among the units have made the Cement units to take
up many thermal energy saving projects. The plants are also looking for avenues
for reducing the cost by replacing the costly fuels with cheaper fuels. The
possible fuels that have been tried by the Cement units include Lignite, Rice husk
and Ground-nut shell.
Previous status
In a million tonne dry process pre-calciner plant, Coal was being used as fuel for
firing in both the Kiln and Calciner. The Coal was having a Calorific value of
about 5900 kCal / kg with a cost of about Rs. 2000 / MT.
Energy saving project
A provision was made to utilise Rice husk in the Calciner. With the new system it
was possible to replace part of the coal fired in the Calciner with Rice husk.
Implementation methodology & time frame
A hopper was installed by the side of the pre-heater building for storing the Rice
husk. The rice husk was fed to this hopper with the help of front end loaders.
The Rice husk was conveyed to the Calciner with the help of a Rotary blower of
32 m3 / hour capacity. The whole system was fabricated with the waste material
available in the plant. The system was hooked up with the main system during a
brief stoppage of the plant. The system could be operated for about 8 months of
non- rainy dry season.
Benefits of the project
The implementation of the project resulted in the reduction of the cost of fuel
used in the Calciner. The cost comparison of Coal and Rice husk are as below;
Parameter Coal Rice husk
Cost Rs.2000 / MT Rs. 750 / MT
Calorific value 5900 kCal / kg 2900 kCal / kg
Energy cost Rs. 340 / MMkcal Rs. 260 / MMkcal
The rice husk was used for replacing about 10% of the total coal used for firing
in the calciners. This resulted in reduction of the total thermal energy cost, with
the other conditions such as output, temperature, pressure etc. remaining the
same. There was also a marginal reduction of the power consumption in the coal
mill, as the rice husk was used directly without grinding. The rice husk becomes
wet and handling becomes difficult during the rainy season. Hence, the usage of
rice husk was restricted to the non-rainy and dry season (about 8 months in a
year).
Financial analysis
The annual benefits (in the form of reduction in thermal energy cost) was about
Rs. 35 lakhs. The equipment required for conveying and firing in the pre-heater
was fabricated in-house with available material and hence the investment was
negligible.
Benefits of using cheaper fuel
· Reduction in thermal energy cost
· Marginal reduction in coal mill power consumption
Cost benefit analysis
· Annual Savings - Rs. 35.0 lakhs
· Investment – Negligible