초록 ▼

Method for freezing a slug of water 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 water through the walls of the pipeline to a cryogenic cooling fluid such as liquid nitrogen. A section of the p

Method for freezing a slug of water 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 water through the walls of the pipeline to a cryogenic cooling fluid such as liquid nitrogen. A section of the pipeline is filled with water and is enclosed by an insulated 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 nitrogen vapor through the pool. Heat exchange occurs as a result of heat transfer directly from the surface of the pipeline to the liquid nitrogen by the action of convection currents produced by the vigorous agitation of the liquid associated with the motion of the nitrogen vapor. In a preferred embodiment, the liquid nitrogen is diffused over the surface of the pipeline by means of a permeable layer of material which is easily wetted by the liquid nitrogen.

대표청구항 ▼

A method of freezing a slug of liquid in a section of fluid transmission line by the transfer of thermal energy from the slug of liquid through the transmission line to a pool of liquid cooling fluid which evaporates when exposed to a predetermined range of pressure and temperature conditions compri

A method of freezing a slug of liquid in a section of fluid transmission line by the transfer of thermal energy from the slug of liquid through the transmission line to a pool of liquid cooling fluid which evaporates when exposed to a predetermined range of pressure and temperature conditions comprising: enclosing the section of transmission line with thermally insulated material to define an insulated chamber around the section; discharging liquid cooling fluid into the chamber until the chamber is at least partially filled by the liquid and at least a portion of the enclosed transmission line is submerged in a pool of the liquid cooling fluid, said step being terminated thereafter during a predetermined interval while the liquid cooling fluid evaporates in response to the transfer of heat from the transmission line, said step being repeated thereafter to replenish the evaporated cooling fluid; sensing the temperature of the surface of the enclosed transmission line as the chamber is filled; said step of discharging liquid cooling fluid into the chamber being repeated to replenish the evaporated cooling fluid in response to an increase in temperature of the transmission line to a predetermined level as indicated by the temperature sensing step; agitating the liquid in the pool; exhausting cooling fluid vapor from the chamber; and sensing the rate of formation of crystals within the slug of liquid as it freezes.