Electrification of an Entrainment Calciner in a Cement Kiln System – Heat Transfer Modelling and Simulations

Abstract

Carbon capture and storage may be applied to reduce the CO2 emissions from a cement plant. However, this often results in complex CO2 capture solutions. To simplify the capturing process, an alternative is to electrify the cement calciner. This study covers the feasibility of electrifying an existing calciner by inserting electrically heated rods in the calciner. An existing entrainment calciner in a Norwegian cement plant is used as a case study. A model is developed to quantify the aspects concerning the feasibility of the calciner. The model first estimates the possible area of inserted rods in the available space. A mass and energy balance is then performed to estimate the heat duty of the heating rods. Further, a radiation heat transfer model is included to identify the feasibility of transferring heat from the rods to the raw meal. Finally, the model includes the design of the heating rod to estimate the required number of heating elements. The results indicate that it is technically feasible to electrify the calciner. The total heat duty of the calciner is 77 MW, with 68 MW for meal preheating and calcining, and 9 MW for gas preheating. 2570 heating rods are required, operating at 1150 °C in the gas preheating zone and 1050 °C in the meal preheating and calcining zone. The feasible heat flux is 26-34 kW/m² for gas preheating, 35-80 kW/m² for meal preheating and 30-50 kW/m² for calcination. However, some challenges related to recuperating the heat from the gas and maintenance of the system must be studied further.