Estimation of the Coke Calcination Yield by Granulometry Analysis

At Rio Tinto operated calciners, the masses of the green petroleum coke (GPC) feed and of the produced calcined petroleum coke (CPC) are continuously measured by belt scales. In spite of frequent calibration, CPC yields based on the measured mass flows are not always accurate. Thus, CPC yields are calculated from GPC deliveries, CPC shipments, and inventory changes. This approach only allows calculating CPC yields over long periods. An alternative method was therefore developed. During calcination, GPC loses humidity and volatiles. Coke fines are entrained by the gas flow and swept out of the kiln or oxidised. The quantity of lost fines can be determined by GPC and CPC granulometry analysis. The CPC yield is calculated from the combined mass losses. Calculated yields agree well with values determined by the long-term mass balances. Furthermore, short-term yield changes can be detected.