| 摘要 |
Apparatus for freezing a slug of liquid to form an ice plug in a section of a pipeline for hydrostatic testing purposes. The ice plug is formed by transferring thermal energy from the slug of liquid through the walls of the pipeline to a cryogenic cooling fluid such as liquid nitrogen. A section of the pipeline is filled with liquid and is enclosed by an insulated housing which defines a cooling chamber. The chamber is filled with liquid nitrogen to form a pool around the pipeline. The liquid nitrogen is agitated by discharging a stream of liquid nitrogen or nitrogen vapor through the pool. Heat exchange occurs as a result of sensible heat transfer directly from the surface of the pipeline to the pool of liquid nitrogen. In a preferred embodiment, the liquid nitrogen is discharged uniformly over the surface of the pipeline as the chamber is filled by means of an insulated header which forms a part of the chamber housing.
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