Periodic cleaning of boiler tubes in heat exchangers - which are used to dissolve alumina in caustic soda lye in bayer process

摘要

Several tanks contain a suspension of bauxite in caustic soda; and the suspensions are fed through several rows of parallel tubes located in a row of heat exchangers. Fluids, e.g. steam, are fed into the heat exchangers to boil the suspensions in the tubes so the alumina dissolves. The solns. are then fed into a single reactor. Another tank contains only aq. caustic soda or water, which is fed through one set of tubes and into the reactor so any deposits inside these tubes are dissolved; this tank is then filled with a bauxite suspensions while one of the other tanks is filled with aq. caustic soda or water employed to clean another set of tubes. All the heat exchanger tubes are periodically cleaned without the need to stop prodn., so heat exchange is not impaired and no separate cleaning solns. are required.