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

Historical Facts Historical fact Since 1924 Since 1924 Moisture and Ash Moisture and Ash Distinctly different from Classification of Coals Distinctly different from Classification of Coals Study Group constituted by GoI in 1962 – proposed UHV= GCV - Ash penalty Study Group constituted by GoI in 1962 – proposed UHV= GCV - Ash penalty CFRI proposed CFRI proposed 1. UHV= 8900 – 138(A+M), kcal/kg,ash & moisture% at 60% RH and 40 o C 2. 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 UHVfor Coal grading system implemented in 1979

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

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

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