Abstract: An improved dump valve construction for a high density cellulosic pulp cleaner. The cleaner comprises an upper separating chamber and a lower reject chamber which communicates with the lower end of the separating chamber. Cellulosic pulp is pumped tangentially into the upper end of the separation chamber and is swirled within the separation chamber to cause the high density contaminants to fall into the reject chamber while the pulp is discharged through an outlet in the upper end of the separation chamber. The opening between the lower end of the separation chamber and the reject chamber can be opened and closed by a sliding upper valve while the lower end of the reject chamber is formed with an outlet and the flow through the outlet is controlled by a dump valve having a curved or spherical outer surface which seats on an annular valve seat bordering the outlet.

Abstract: A papermaking water system utilizing vacuum pump sealing water and having a zero sealing water discharge. A group of water seal vacuum pumps are used in a papermaking machine to generate subatmospheric pressure in suction equipment and thereby extract water from a wet paper web. During operation of the vacuum pumps, the sealing water is heated and the heated water is discharged to a cooling tower to cool the water which is then recirculated to the vacuum pumps. Steam from a generating plant is supplied to the dryer drums in the dryer section of the papermaking machine, and the steam condensate is combined with the heated sealing water flowing to the cooling tower. By using steam condensate as makeup water, no ionic buildup will occur in the closed system, and high quality water is withdrawn from the closed system and may be used in other sections of the papermaking machine, so that there is no discharge of sealing water to the sewer system.