Intermittent press in one or more levels for board prodn has groups of piston/cylinders linked to medium and low pressure vessels which have a closed nitrogen supply system to prevent or eliminate nitrogen loss

摘要

The intermittent press, and especially a single- or multi-layer press structure, has piston/cylinder units which act on the press plates. The first group (4a) of the piston/cylinder assembly (4) is linked to the medium pressure vessel (6) through a medium pressure line (12a). A second group (4b) of piston/cylinders is linked to a low pressure vessel (5) through a low pressure line (12b). The two pressure vessels (5,6) are linked together by a nitrogen supply system (13,14) to form a closed pressure system. The nitrogen supply system has at least one nitrogen line (13) between the medium pressure (6) and low pressure (5) vessels. A nitrogen charging unit (14) is in the nitrogen line (13), such as a compressor. The piston/cylinder assembly (4) has an outer medium pressure group (4a) and an inner low pressure group (4b). Both pressure lines (12a,12b) each have a control valve (9,10).