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‘ New Air Pump of Simple Construction NEW and interesting type of air Kqui U A pump for producing a_ high vacuum economically was re- cently introduced by the C. H. Wheeler Mfg. Co., Philadelphia. The new device is designed to per- form the work of any air pump work- ing on the dry air principle. It has no piston or valves. It is operated by live steam jets which, by passing through nozzles of special design, ob- tain a high velocity and entrain the air and non-condensable gases from the condenser, compressing them to atmospheric pressure. One of the accompanying illustra- tions shows one of these air pumps for a surface condenser condensing about 20,000 pounds of steam per hour. This pump. is extremely small, requires little space, and is light. A diagrammatic arrangement of these air pumps, as used on marine surface condensers for turbines, is shown in the other illustration. The exhaust steam from the air pump is discharged into the feed tank in a condensed form, and serves to raise the temperature of the feed water. By this arrangement, all heat con- tained in the live steam used for operating the pump is utilized, thus giving a thermal efficiency of practi- cally 95 per cent. The condensed steam is taken from the hotwell of the condenser by a turbine or elec- tric-driven condensate pump and is discharged into the feed water tank, where it mixes with drains from other auxiliaries and with the exhaust steam coming from the air pump. A sep- To Feed Pump lrbire river? Conderisare Funp arating wall with an overflow is pro- vided to force the water to rise, thereby freeing the air which escapes through a vent arranged on the top cover of the feed tank. The air pump may be located at any convenient place close to the condenser. The air suction should be arranged a little higher than the air suction of the condenser, so as to form a drain to- wards the condenser. An automatic steam pressure reg- ulating valve, supplied -with the air pump, is arranged somewhere in the highest point of the live steam line. Its purpose is to maintain a constant steam pressure at the inlet of the air pump, thereby insuring a_ uniform steam consumption with varying boil- er pressure. The back pressure on the exhaust of the air pump should not exceed Y%-pound gage. A _ circulating pipe with a float-operated valve is shown in the diagram. The- object of this circulating pipe is as follows; if the main engines of a marine installation come to a sudden stop, as frequently occurs when maneuvering, very little water will be discharged by the con- densate pump to the feed tank. As the air pump is in operation, steam will continuously enter the feed tank. The heat contained in the steam will cause an increase in the temperature of the water in the feed tank, and the water would soon reach the boil- ing point unless some _ additional water supply is provided for. The float-operated regulating valve and the circulating pipe serve this pur- ° ° ° 00000 00000000000000000000000° 9°e00000000 peeaaQose@eoreooes ° ° ° oO ° DIAGRAMMATIC ARRANGEMENT OF AIR PUMP FOR MARINE SURFACE CONDENSER 154 pose. AIR PUMP FOR SURFACE CONDENSER As soon as the quantity of water supplied to the feed tank be- comes smaller, the water level in the first compartment of the tank will fall, thereby opening the automatic regulating valve and allowing some water to be sucked into the condenser through the circulating pipe. This water by falling down over the cooled tubes will be reduced in temperature and will be returned by the conden- sate pump to the feed tank, thus pre- venting boiling. The air pump may also be used with advantage with reciprocating engines where a lower vacuum than that provided for on turbine installa- tions is required. The reciprocating air pump, which is generally operated directly by a lever connected with links to the crosshead of the main engine, may be _ replaced by the Wheeler air pump for removing the air, with a small direct acting hot well pump for removing the con- densed steam from the condenser. Among the advantages of this new device is its simplicity and conse- quent ease of manipulation and op- eration. The apparatus is static. All that is required to start the device is to open the steam valve; to stop it, to close the valve. The complete absence of internal moving parts eliminates wear, while the flexibility in locating the appa- ratus is of considerable importance in marine installations.