Cement and Energy

SHREE CE~IENT BREAKING BARRIERS OF KILN PRODUCTIVITY AND ENERGY CONSERVATION * M.K. Singhi, S.S. Jain andDr. S. N. Yadav Shree Cement Introduction E nergy conservation and productivity enhancement in a cement plant is achieved either by modernising and upgrading major equipment or by a continuous process of optimisation by incorporating small changes in existing process ~ircuits. Generally, significant energy conservation is achieved through large scale investment by the introduction of new equipment or system. Such modern isation involves a one-off heavy outlay. The alternative is a systematic phased modernisation with appropriate methods where implementation can be carried out using in-house experti se and capabilities. The approach reduces downtime and provides an opportunity to verify the outcome of each stage before going on to the next. A practical example has been achieved by Shree Cement, with improved producti vity and energy conservation through several steps taken in-house. The 1800-tpd FLS kiln with 4-stage SP and ILC was installed in 1985 and had been operatin g wi th an average energy consumption of 114 to 11 8 kWh/t of cement. Step-by-step modernisation has achieved a reduction in power consumpti on to 86-9 1 kWh/t of cement while production has increased to 356 1 tpd with a specific loading up to 6.43 mtpd/m 3 which is reported to be one of the best in the world. Modernisation The dry process plant was rated at 1800 tpd of clinker and the equipment suppli ed comprised an Atox mill for raw material grinding. CF silo, kiln equipped with 4 stage suspension preheater and in-line precalciner and Fo1ax grate cooler, Atox coal mill , and Combidan cement mill. *Reproduced from World Cemem, Auliusr 1997 Fig. I New LP cyclones and ESP cooler installed One of the most important features of the phased modernisation programme was the replacement of the first-stage conventional twin cyclones in the preheater with LP cyclones through indigenous design, fabrication and installation at the top of the preheater (Fig. I). The LP cyclones and riser duct (from the second stage to the first stage) were preassembled and bricklined at ground level, then assembly of the cyclones (125 t each) and riser duct (95t) were lifted and installed on top of the 74.2m high preheater tower by means of a heavy-duty crane thus saving 50% downtime of the kiln , the job being executed in only 22 days. This is reported to be the first job of its kind in the cement industry. Table 1 iternises the programme of upgrading and modernisation of equipment. The modifications mentioned in the current year were incorporated during May 1997. Significant improvement in various parameters relati ng to specific energy consumption has been observed and it is expected that overall producti vity of the plant will improve further. 8 • ..