GRADING of POWER COALS

1. GRADING of POWER COALS dr kalyan sen Former Director, CFRI-cum-CMRI, Dhanbad Prof Emeritus, BESU Shibpur. COALCONNECT,Nov.2007,Kolkata

2. Historical Facts Historical fact • Since 1924 • Moisture and Ash • Distinctly different from Classification of Coals • Study Group constituted by GoI in 1962 – proposed UHV= GCV - Ash penalty • CFRI proposed • UHV= 8900 – 138(A+M), kcal/kg ,ash & moisture% at 60% RH and 40o C • UHV = 8900 – 138(A+M) – 150(19.0-VM) ’’ for LVLM coals, ash, moisture and VM as analysed basis. • UHVfor Coal grading system implemented in 1979

3. Shortcomings of UHV • Based upon coals av.in 1960s – generally Jharia, Bokaro coalfields, where GCV of pure coal ~ 8900kcal/kg • Combustion data from Stoker fired boilers • UHV = 0 for A+M = 64.5% • UHV = ( - ) for High ash coals, suitable for Fluid Bed Boilers, ash >65% • UHV > GCV for low ash washed coals for ash < 10%

4. New System - Proposed • GCV, as recd basis, determined for every consignment as per ISO/BIS, by lab analysis. • “ash penalty” mainly depends upon efficiency of combustion boiler, • Additional parameters : ash and moisture as shown in the matrix (next slide) • Sulphur may be considered as discrete parameter.

5. Thank You