GB743713A - Improvements in or relating to vessels for carrying bulk oil - Google Patents

Abstract

743,713. Tankers. SHELL REFINING & MARKETING CO., Ltd. Dec. 22, 1953 [Jan. 13, 1953], No. 1042/53.. Class 113. [Also in Group I] In a vessel for carrying bulk oil in a tank or tanks having means for washing the tanks and also for causing the oil and/or sludge removed by the washing operation to separate from the washing water, means are provided for so collecting and storing the separated oil and/or cludge that it is isolated from the oil carried as qargo and also from the ballast until subsesuently discharged from the vessel to a disposal installation, means also being provided for separating oil and/or sludge from the ballast water of ballasted oil carrying tanks and for collecting, storing and disposing of this oil and/or sludge with, or in the same manner as the oil and/or sludge from the tank washing operation. The vessel has centre tanks 1c, 2c, 3c, 4c, 5c, 7c, 8c, 9c, 10c for cargo with port and starboard cargo wing tanks 2p, 3p, 6p, 8p, 9p and 2s, 3s, 6s, 8s, 9s which may be put in communication with their adjacent cargo centre tanks by means of levelling valves 2l, 3l, 8l and 9l. The wing tanks 1p, 4p, 5p, 7p, 10p and 1s, 4s, 5s, 7s, 10s are for clean water ballast and each has a valve 17v therein for communication with the ballast water line 17p-17s. A cargo stripping line 18 has transverse branches 18t and valves 18v permit communication between all cargo tanks and this stripping line. Oil cargo lines 19, 20 and 22 which may be connected by valves 21 and 23 supply cargo directly to the centre cargo tanks through valves 19v, 20v and 22v respectively and indirectly to the wing cargo tanks through valves 2l, 3l, 8l, 9l. The midships centre tank 6c (see also Figs. 2 and 3) comprises a fresh washing water compartment 11, two separation compartments 12p and 12s, a sludge compartment 13, a sludge pump room 14 and a sump 15 with a valve 15v which provides communication between the sea and the piping system. The longitudinal bulkheads 25 which divide the separation compartments from the sludge compartment 13 are topped by sill plates 26 which leave clearance for the contents of the separation compartments to spill over into the sludge compartment. Immediately aft of the tank 10c is the cargo pump room 16. When cargo wing tanks are ballasted, oil left in the tanks will float on the water. To empty these tanks the ballast water is run down to sea level, the bulk of the remainder then being discharged overboard by the cargo stripping pumps or the sludge pump via the cargo stripping line 18 and sea valve 15v. The liquid then remaining is discharged into the sludge compartment where oil floats on the water which is discharged overboard by the sludge pump after the mixture has been heated to effect separation if necessary. To wash the cargo tanks wash water is delivered from the compartment to the washing machines. The mixture of oil and water then extracted from the cargo tanks enters the separation compartments through an upwardly directed pipe to facilitate a rapid separation of oil. The supply to the washing machines can be augmented by drawing water from the bottom of the separation compartments.