GB1247013A - Dewatering machine for manufacturing a fibrous web, and method of using the same - Google Patents

Abstract

1,247,013. Papermaking. J. M. VOITH G.m.b.H. 2 Aug., 1968 [2 Aug., 1967], No. 36978/68. Heading D2A. A machine for making a web of fibrous material from a suspension of fibres has a duct from which air can be excluded, and through which the suspension can flow, the duct being delimited on one side by a movable webforming wire, and on the other side converging towards the wire at an angle of 15‹. The duct has individual suction devices or groups of adjoining suction devices, the uppermost region of at least one suction device or at least one group of devices having a vacuum connection with a separating vessel at a pressure lower than that inside the suction device, or group. A device is provided to meter the rate of flow of water through the discharge line from the particular suction device or group, and a throttle with automatic means for varying it as a function of the rate of flow, to keep that rate constant. Several such devices or groups of devices can be controlled in this way, their vacuum connections leading to a common air-separation vessel. The side of the duct away from the wire may be defined by a water-permeable member, e.g. a second wire with its own suction devices or groups of suction devices controlled in the same way, but with the divisions between the devices or groups on one side of the duct staggered with respect to those on the other side. The velocity of the suspension at any point in the duct can thus be held constant, and the velocity profile along the duct can also be held at a desired form, e.g. constant. The invention can be applied to a twin-wire machine (Fig. 3, not shown), a multiple-wire machine with top drainage arrangements (Fig. 5, not shown), a cylinder machine (Fig. 6, not shown) or a rising-wire machine (Fig. 7, not shown). Reference has been directed by the Comptroller to Specification 1,143,604.