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Equipment Used Atloat, Ashore An Oil Separator for Bilge and Ballast Water— Tested at Naval Engineering Experiment Station l ie of fuel oil on shipboard has resulted in pollution of harbor waters, with attendant destruc- tion of fish and material increase in the fire hazard of harbor property. This problem has become so serious that the last congress passed a law prohibit- ing the discharge of oil or water con- taining oil into coastal waters of the United States and- territories. Thus a vessel approaching these shores must pump ballast water from oil tanks some distance at sea. This procedure means loss of time if the ship lays to outside of the limits a x g : é ‘Filter Space f | tiled with Broken Forrery Second-Srtage Compaortiné First-Stage Compartinent DIAGRAMMATIC ARRANGEMENT to pump tanks; or if pumping is started some distance at sea the sta- bility of the boat is materially de- creased, which from an_ operating standpoint is inconvenient and may be a dangerous procedure in_ heavy weather. Various methods of elim- inating the oil from the discharge water have been suggested, one of the most interesting of which is the “Rocket” oil separator, which was recently tested at the United States naval Engineering Experiment station. The separator tested had a designed WwW. J. Barnes is associate mechanical engi- neer, U. S. naval engineering experiment sta- tion. Presented before the American Society of Mechanical Engineers at Annapolis, Md., Novy. 1, 1924. BY W. J. BARNES capacity of 50 long tons or 13,450 gallons of liquid per hour, and was manufactured in England under di- rection of the inventor, H. M. Alex- ander. It is of the gravity type and depends entirely for successful opera- tion upon the difference in density of oil and water. In actual construction the separator has four distinct stages in which separation takes place, as shown in the accompanying sectional eleva- tion. The mixture of oil and water is introduced into the feed. box through the inlet’ nozzle marked A, \| 7hirassroge ' Wy Compartment tilled with Lottery ng Seconastape Heating Coll ” 4" Bore WI Pipes Sy g ‘Drain Pipe WL. from Scum Guiter <-/2" Bore LP BrassCock OF “ROCKET” OIL SEPARATOR and after passing over the weir and through the expanded-metal screen, it flows through the pipe B-C, passes the deflector D, and enters the first- stage compartment, where the major portion of the separation takes place. The oil rises to the top of the cone and when a sufficient head is built up, it overflows the circular weir into the annular oil-seal section, and passing through the oil-discharge pipe, is conducted from the separator. The water from the first stage, which still contains an appreciable amount of oil, passes into the sec- ond-stage compartment from the bot- tom of the first stage and through four 4 inch risers, the entrances of 38 which are near the bottom of the first-stage compartment. Deflector plates are provided at the outlet of each riser. Further’ separation takes place in this compartment, the oil rising to the top and passing through the 2 inch pipe nozzles into the oil-seal compartment and thence out of the separator. The water passes out of the bottom of the sec- ond compartment through an annu- lar space between the first-stage and the second-stage compartments, and thence over a circular weir into the third-stage compartment. This com- partment is filled with broken glazed pottery. The water passes downward through this compartment and out at the bottom; then, rising through an- other annular space and passing over another weir, it enters the top of the fourth-stage compartment which is also filled with crockery. The water passes down through this com- partment and enters the 7 inch water- outlet pipe which is located at the bottom of the casting. It then rises to the bottom of the discharge cham- ber of the feed box and, falling over another weir, enters the outboard de- livery line of the separator. Gravity Flow is Used The flow of the water and oil through the separator is entirely by gravity. The crest of the outlet water is 6% inches below that of the inlet, the head thus provided be- ing sufficient to maintain a_ steady, even flow without the necessity of any manual adjustment or regulation. The construction of the feed box permits any entrained air in the mix- ture to pass off before entering the first stage. Any air or vapors that are thrown off during further sepa- ration are carried away through the air vents provided as shown. In the tops of the first and second- stage compartments are located two heating coils controlled by suitable valves, 1, 2 and 3. Valves 4 and 5 control the steam supply to the scrub- ber lines in compartments 3 and 4, respectively. Condensed steam from the coils is discharged through pipes to a header and thence through a steam trap to the hot well. Under normal operating conditions, steam will be supplied to the first