The invention relates to a centrifuge for the clarification and separation of liquids, having one or more paring means for the removal of the clarified or separated liquids, having a stationary inlet tube communicating with a smooth, cylindrical inlet chamber, rotating with the drum and fixedly attached thereto, through an opening which is slightly larger than the inlet tube, and outlet ports emerging from the inlet chamber, and discharging into a forechamber which communicates on the one hand through ventilation passages with an annular chamber preceding the inlet chamber, and on the other hand, with the riser passages of the plate insert disposed in the centrifuge drum.
A centrifuge drum of this construction is disclosed, for example, in Swiss Pat. No. 236,747, and was intended to serve so that whole milk could be fed in a gentle and smooth manner to the centrifuge drum so as to prevent the fat globules in the milk from being broken up when the milk enters the drum, since this has an adverse effect on the separation of whole milk into cream and skim milk. This is because the more severely these fat globules are broken up, the greater will be the fat content in the separated skim milk. Furthermore, the entrainment of air at the inlet to the drum is to be largely prevented, since this also interferes with the separation of the milk in the centrifuge.
It has been found, however, that a centrifugal separator drum constructed in this manner is unable to prevent the entrainment of air nor the breaking up and brusting of the fat globules in the milk, nor of other suspended particles or dispersed droplets of the liquids which are to be clarified or separated. The more severely the liquid droplets are broken up the greater will be the centrifugal force needed for the separation, which can be produced, for example, by increasing the drum rotational speed or by increasing the separation surface in the drum.
It is for the reasons given above that airtight centrifuges have been developed, such as those disclosed in German Pat. No. 2,508,503. Such airtight centrifuges are provided with sealing sleeves, frictional ring seals or the like, at the inlet to the drum, so that the inlet of the drum is hermetically sealed against the atmosphere. Owing to the fact that the liquid being centrifuged has to be fed under pressure to these airtight centrifuges, the entire drum is filled with liquid and is under a certain liquid pressure so that a largely gentle and smooth flow of the liquid in the centrifugal separator drum is assured.
The chief disadvantage in airtight centrifuges is to be found, however, in the seals between the stationary inlet and the revolving drum, these seals being subjected to great wear at the high rotatory speeds commonly used today, and have to be constantly cooled or lubricated by liquid during operation. Furthermore, the separators are very expensive to make on account of these seals, and the seals themselves require careful maintenance and treatment.