Cement Energy and Environment

General Plant Air A lot many plants have two to three big compressors lor plant air. Usually, i r two compressors are operating to supply all the plant ai r, when I 0 more cubic metres per hour arc required, the third compressor, which may be a large 100 cubic metres per hour compressor, comes on line. Thi s is an incrficient practice. A bellcr system would be to modulise compressed ai r systems with many smaller compressors of different sizes. .A computer would control wh ich compressor goes on line to suppl y addi ti onal air. Usually six to eight compressors wou ld be involved ranging in size from 30 to 50 cubic metres per hour. Plant ai r power consumption could be reduced from 9kWmin/cubic meter of ajr to 6kWmin/cubic meter or air. This would represent an annual energy saving of nearly 34 per cent. time of each compressor, thus keeping the running time of a! I compressors balanced. The payback period depends upon the condition of the existing general plant air compressors and the cost of electric power. Calcu lations show that in many cases, the capital invested can be recovered in just I .5 to 2.0 years, and as mentioned, the project can be executed in phases, if availability of in vestment capital is limited. Phast I moderrusovo" l Jorre compresson pJus 1-4 smolUNU Phose 2 modemesoliOtt I lot-te comprtssor plus 4-6 smol urvts Phose 3 modemisaliOn 6-8 smoN compressor unns only Conversion to a modulised system can be done in steps. First, one could replace one old and inefficient compressor by two or Figure 3 Typically fully automated computer-regulated modulised general plant air compressor station showing the steps involved to achieve mbstantial power savings three small compressors. Then, in the second and th ird steps, al l remai ning old and inefficient general plant air compressors could eventually be replaced. Figure 3 illustrates such a phased conversion and the power savi ngs wh ich wuld accrue from each phase. A computer regul ates the entire system bringing on, through pressure sensors, the required addi tional compressor. The computer llso memorises the running Conclusion and Technical Audit Millions of dollars of operating expenses per year can be saved in a wet process cemen t plant. Every plant should order a technical aud it to determine where money can be saved, how much modernisation would cost, and how fast the investment will be recovered. The val ue of a wet cement plant would rise considerably when the requisite energy saving systems arc in place. ENERGY EFFICIENCY CONSULTANCY AND PROJECTS ENTERPRISE • • • • Total energy services incl uding : Energy audit and consulting, Perrormance contracting. Project linancing. and Project implementation, on the lines of the energy services concept in North America. will now he available to industri es including cement in India. These wi ll be provided hy DSCL Energy Services Company Ltd (DESCL), an enterpri se of DCM Shriram Consolidated Ltd (DSCL), launched in November 1998. 9