Abstract: Oxygen delignification of paper pulp (comminuted cellulosic material in a slurry) at medium consistency (i.e., about 6-18%) is practiced without the necessity of a separate mixer. The pulp is drawn into the inlet of a fluidizing centrifugal pump capable of pumping medium consistency pulp. The pump typically has a vacuum system associated with it for effecting degassing of the pulp. As the pulp is pumped out of the pump outlet, oxygen gas is added to the pulp. This is accomplished utilizing a shear plate having a central opening and one or more radial bores, oxygen being introduced under pressure into the bores to pass into the pulp flowing through the plate central opening. A tube may be disposed in the bore(s) and have an oxygen permeable portion (such as a porous stone or sintered metal) extending into the central opening in the plate, the oxygen being introduced in the form of very small bubbles by the oxygen permeable portion.

Abstract: A flash tank, and method of flashing steam utilizing the tank, result in minimum foam generation so that the outlet steam remains uncontaminated. Feed fluid fed into the interior of the tank is positively prevented from splashing into the liquid seal provided adjacent the liquid outlet from the tank. This may be done by directing the feed fluid upwardly when introduced into the tank, and providing a liquid holding tank externally of the flash tank, feed fluid impacting upon a deflecting member and then the conically downwardly tapering walls of a bottom portion of the tank. Another alternative is to feed the feed fluid downwardly into the tank to impact upon a conical deflecting member so that there is minimum loss of momentum of the feed fluid, and again it impacts upon the conically tapering walls of the tank bottom portion.