FORMATION OF FLAMMABLE-GAS MIXTURES IN EX TRACTION TOWERS AND PROCEDURES FOR ITS AVOIDANCE

In the 1993 campaign a deflagration occured during welding works in th e area of the tower extraction plant in one of the Sudzucker factories . Measurements that were thereupon arranged for in the headspace of th e extraction towers showed a formation of an inflammable gas in alarmi ngly high concentration. The detailed examination revealed hydrogen as the main component of the gas. Organic components, e.g. methane, alco hols, etc, could only be found in traces. Hydrogen is a metabolic prod uct of thermophilic, anaerobic bacteria, known as clostridia. In the m iddle of the 1960s an infection of clostridia was observed in Austrian sugar factories. Due to the common practice of sulphurizing in those days, this resulted in formation of hydrogen sulphide gas in the extra ction. In that case the gas formation could be suppressed by injection air into the extraction towers. As this report shows, the unwelcome f ormation of hydrogen can also be effectively combatted by injecting ai r into the extraction towers. The way of proportioning the air injecti on is described. Additionally, the examinations that are carried out u p to now give some hints about possible technological advantages. They are also described in the report.