| 摘要 |
<p>1,207,770. Pipe-line pig trap. SHELL INTERNATIONALE RESEARCH MAATSCHAPPIJ N.V. 8 Sept., 1969 [9 Sept., 1968], No. 44283/69. Heading F2N. A pig trap comprises a housing 1 connected by a flange 2 to a pipe-line and having a branch 6 connected to a tank, a by-pass 10 from the housing bottom to the branch, and a sleeve 7 for catching the pig slidably arranged within the housing 1 such that the sleeve in its rest position leaves the passage between the pipe-line and the branch 6 open by way of registering ports 9, 4, and when moved to its opposite position, shuts off this passage. Wall friction between the incoming pig and the sleeve 7 moves the sleeve against a spring 8, the remaining liquid in the pipe has been removed via the by-pass 10 to the branch 6. When the compressed fluid (which may be liquid or gas) propelling the pig is turned off the sleeve 7 returns to its rest position. The pig is dispatched in the opposite direction by pumping compressed fluid through a line 11 (a valve 12 closing the by-pass 10) to move the piston 15, connected to the sleeve 7, downwards to close the passage 4, 9. In a further embodiment, the sleeve 27 consists of two parts 28, 29 urged apart by a spring 30 to provide a passage between the pipe-line and the branch. When the incoming pig moves part 28 by wall friction to abut the part 29, the passage is closed and part 28 is retained against part 29 by the action of the compressed fluid on its upper surface. In a modification of this embodiment to allow for interruption of the operation sequence, with the pig positioned between the traps, part 29 is connected to a piston to which compressed fluid is supplied to close part 29 to part 28 to permit build up of pressure to propel the pig. Alternatively, the sleeve 29 may be closed at its lower end and have a throttled connection therethrough for the propelling fluid expelling the pig, and a passage with a check valve permitting escape of liquid to the by-pass from in front of an incoming pig.</p> |
