ENERGY-SAVING BY SMALL CHANGES IN THE NETWORK OF CONDENSATE-HEATED JUICE PREHEATERS

In the 1991 campaign in the Larissa factory of H.S.I., having a daily beet slicing capacity of 7,200 tonnes, an energy saving system was ins talled utilizing the heat content of condensates and using some existi ng tube preheaters not been used for ten years. These preheaters had b een used for heating raw juice prior to preliming and they were connec ted in parallel. Because of the low juice velocity and the presence of pulp particles rapid clogging of the preheaters occurred which needed frequent cumbersome cleaning by hand. Another site of juice preheatin g was therefore chosen, i.e. after preliming. A connection in series w as made together with instituting a reduction of the juice recirculati ons in the preheaters to achieve a velocity of approximately 1 m/s. Du ring the whole campaign there was no need for tube cleaning at all. Th e temperature of the condensate decreased from 106-degrees-C to 62-deg rees-C, while the temperature of prelimed juice increased from 50-degr ees-C to 80-degrees-C. The final heating up to 86-degrees-C was made u sing vapours from the 5th and eventually, if needed, from the 4th stag e. The beneficial results were the following: Better washing of the ro tary filters' cake. better purification effect, increase in thick juic e dry substance, reuse of equipment which had been left as obsolete, d ecrease in fuel consumption, small expenses for changing the network, increase in sugar recovery and good heat transfer coefficients. The ab ove can be considered as an application of the 'pinch' technology.