Aerostatic pump seal

Process pumps commonly utilize water-lubricated mechanical face seals. The seal faces are commonly silicon carbide or other durable materials. However, the reliance on water flush for the lubrication of the seal poses challenges due to wear. The wear is result of abrasive particles and corrosion problems originating from the leaking water. To address these issues, this paper investigates the feasibility of an aerostatic seal system. The proposed seal comprises two aerostatic seals mounted to a pressure-fed chamber: one facing the pump chamber and the other facing the ambient. Both of the sealing surfaces are flexibly supported and preloaded against the seals. A chamber between the seals is pressurized, which causes flow through the air gaps of the seals towards the ambient and the pump chamber. The flow prevents pump chamber liquid from leaking into, and through the seal. Thus, only seal supply gas is exhausted to the ambient. The feasibility of the seal concept was validated experimentally. The seal air consumption, leakage, and pressures in various parts of the system were measured. The application of this type of seal in the paper industry, particularly for pumping cellulose-liquid mixtures using centrifugal pumps, could reduce the frequency of seal replacements and eliminate water leakage.