| abstract |
In a filtration apparatus for concentrating acidulated milk, a filter unit is located between a pump and a backpressure valve. The pump used is a displacement pump, even though the liquid to be filtered would, according to its viscosity value, permit a conventionally used centrifugal pump. During an operating period, the backpressure is gradually increased so that, in spite of increasing coverage of the filter with suspended, dissolved or emulsified constituents, the permeate flow through the filter remains constant. Owing to the characteristics of the displacement pump, the delivery rate remains the same in spite of the increasing backpressure, so that the purification effect of the delivered liquid on the deposits in the filter also remains the same. An extension of the possible duration of an operating period is achieved in this way. <IMAGE> |