AbstractTheoretical expressions were developed for the design of a tubular reactor for the calcination of limestone, pneumatically conveyed by flue gas. The total residence time and the length of the reactor are affected in particular by the particle size, the excess thermal capacity of the gas and the heat transfer coefficient. High throughput can be achieved in relatively small reactors.An experimental investigation verified a theoretical prediction, that a considerable part of the decomposition takes place in the first few centimeters of the reactor length. The rate of heat transfer in this section was high, with Nusselt numbers of 9.9 to 31.7.