Most of the small scale steel re-rolling mills in India are based on pulverized coal (fuel) for heating of raw materials like ingots, billets, blooms or scrap. There are around 1200 rolling mills in India out of which around 300 steel re-rolling mills are operating in the state of Punjab where around 4 million tons per annum of steel products are rolled using 2,44,000 MT pulverized coal as fuel worth Rs. 3400 million.
In a reheating furnace, combustion/flue gases generated from the combustion of pulverized coal leaves the furnace at very high temperature along with sufficient concentration of suspended ash particles. These furnaces operate at a thermal efficiency of 20-30%, resulting in wastage of precious heat energy. Various energy audits reveal 30-40% heat losses from flue gas only leaving the furnace at a very high temperature (400-650oC). Besides this, substantial heat is lost from furnace walls, inspection and discharge door and inform of un-burnt carbon in the pulverized coal. Fuel consumption can be reduced minimum by 10% i.e. with Rs. 340 million by utilizing waste flue gasses & by implementing other workable Energy Conservation Measures such as insulation furnace & openings, usage of pulverized coal above 200 mesh & provision of requisite implementation. Further, flue gases contribute to release of 6.70 lacs tons of CO2 and 3000T of SPM into the environment per annum from 300 steel re-rolling mills.
Council Contribution in Rolling Sector :
- Performance evaluation of various APCDs installed in 2003.
- Technology finalized for air pollution control in pulverized coal fired re-rolling mills in 2003
- Arranged the visit of experts from Netherlands for providing expertise on burners for pulverized coal fired mills in 2004.
- After its approval by PPCB, consultancy offered to 191 mills in 2004-2006.
- Demonstration of energy conservation measures in re-rolling mill in 2007-2010 under the project sponsored by Petroleum Conservation Research Association (PCRA) for :
- Better design of re-heating furnace
- Improvement in pulverization of coal
- Effective insulation design
- Shell and shell type waste heat recovery system (Recuperator) for heating capacity less than 7T/hr.
- Instrumentation to control temperature of soaking zone in furnace
- Demonstration of Shell and shell type waste heat recovery system (Recuperator) for heating 8-12T/hr under project sponsored by Department of Science and Technology (DST) in 2011-12.
- Providing Consultancy for energy conservation to re-rolling mills from year 2012.
- Started capacity building training programmer (CTBT) and development of IEC material for rolling sector.
- 25-50 kg of dust is getting entrapped daily in the APCD of an individual unit based on production capacity. After the replication of this technology in all the 300 rolling mills in Mandi Gobindgarh/Khanna, around 10-12 T of dust per day would be entrapped in the APCDs thereby saving the environment in great deal from degradation.
- Earlier due to ineffective suction by local made ID fans, the smoke was seen bulging out from the furnace doors thereby affecting the worker’s health. With the adoption of council’s technology, there has been no smoke from furnace doors due to effective suction resulting in improved working conditions vis-à-vis enhanced productivity.
FUTURE TRUST AREA FOR ROLLING MILLS :
- Total savings of Rs. 500/T of material on account of reduction in:
- Direct scale loss
- Specific pulverized coal consumption
- Increase in production by 10% besides improved quality of the product.
- Reduction in cold startup time by 15-20 minutes.
Based on council’s experience in rolling mills, council foresee to work in following areas:
Contact persons :
- CTBT including energy audit to sensitize the rolling mill w.r.t.
- Optimum utilization of infrastructure relating to energy and environment protection with an aim to reduce the scale loss, minimize the fuel consumption and to reduce the pollution load.
- Train the shop floor workers on better feeding firing and operating practices with an aim to improve the coal startup operation.
- Demonstration of improved coal pulverizing system,
- Burner for pulverized coal
- Electrical audit in rolling mill.
- Demonstration of automation to control the furnace temperature and excess air
Mr.Pritpal Singh, Senior Engineer, Cell No. 098141-04784 Email :firstname.lastname@example.org
Er. Ranjit Singh, email@example.com