A press comprises two cooperating rolls, which form a nip between them. The rolls are located in a vat, to which the material suspension is supplied. The rolls are formed with liquid permeable shell surfaces, so that the suspension is dewatered by pressing liquid into the rolls by means of an overpressure. The final dewatering to attain the desired dry matter content of the material takes place in the nip. The dry matter content can amount to 35-55%.
The rolls immersed into the vat are rotary and are disposed on two parallel shafts, and the vat encloses at least the lower half of the rolls. The material suspension is supplied to the space between the vat and rolls from the bottom of the vat. In order to distribute the suspension uniformly along the entire length of the rolls, the suspension is supplied through a plurality of inlets distributed along the bottom of the vat. The number of inlets depends on the axial length of the rolls, but is usually from about 2-6. A central supply pipe is normally connected to a transverse distribution pipe, which communicates with the inlets.
This structure is simple and yields a very uniform distribution of the material suspension, which is an essential requirement for uniform dewatering, as well as for the quality of the dewatered material. The structure, however, does not allow access to the space between the vat and rolls, for example for the cleaning of clogging which occurs in certain cases. Separate openings or manholes in the vat bottom can certainly allow for limited access. However, in many cases, this is not sufficient for eliminating the clogging. It then becomes necessary to dismantle the press, which, of course, is a complicated and expensive operation.
The present invention offers a solution to the aforesaid problem without giving up any of the advantages thereof.