METHOD OF OPERATING HEAT EXCHANGER APPARATUS COMPRISING A PLURALITY OF HEAT EXCHANGER UNITS CONNECTED IN SERIES

摘要

A method is described of operating heat-exchanger apparatus comprising a plurality of heat exchanger units which are connected together in series for countercurrent flow of respectively a first heat exchanging medium which contains fluidizable particulate material and a second heat-exchanging medium. Each said unit comprises at least one vertical tubular duct in which said first heat-exchanging medium flows upwardly with said particulate material in a fluidized state and a compartment through which said second heat exchanging medium passes and through which said duct extends. The particulate material acting to remove deposits formed on the tube inside walls by the first medium. In order to achieve cleaning of the tubes in cases where a high rate of deposit occurs, flow of said second medium through each of the compartments is intermittently interrupted for a period of time, while flow through at least one other of said compartments is maintained. Thus the cleaning effect of the particles is increased in the tubes of the compartment for this period of time.