Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
  • F17D—PIPE-LINE SYSTEMS; PIPE-LINES
  • F17D3/00—Arrangements for supervising or controlling working operations
  • F17D3/14—Arrangements for supervising or controlling working operations for eliminating water
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
  • F17D—PIPE-LINE SYSTEMS; PIPE-LINES
  • F17D1/00—Pipe-line systems
  • F17D1/02—Pipe-line systems for gases or vapours
  • F17D1/04—Pipe-line systems for gases or vapours for distribution of gas

Definitions

• the invention relates to a method according to the preamble of claim 1.
• telescopic pipes After completion, telescopic pipes are often subjected to a pressurized water test to test the resilience and tightness of the pipe. Even after repeated pigging of the line, water remains on the pipe walls, which can lead to corrosion in the long term. Even with other lines that are not subjected to a pressure water test, water can get into the interior of the pipe during transport, storage and assembly, which must be removed.
• vacuum drying has been used in the drying of telescopes.
• the use of the vacuum has the advantage of a high diffusion speed and thus relatively faster drying and a good depth effect. Moisture that has accumulated, for example, in duplications of the pipe wall, in material pores, surface grooves or micro cracks can be evaporated and removed by a vacuum.
• a closed line section is evacuated with a vacuum pump, evaporation commencing after reaching a certain negative pressure, so that water vapor increasingly takes the place of the extracted air, which is subsequently sucked off proportionally with further pressure reduction.
• a purge gas for example also dry ambient air, is let into the pipeline. If desired, the procedure is repeated.
• the object of the invention is accordingly to provide a tube drying method using vacuum, which provides high-quality drying in a manageable and clear process over the entire length of the line.
• this object is achieved with the method according to claim 1.
• This solution provides that the purging does not take place from the evacuation point, but from a remote point and at the same time also with an at least initially restricted addition speed or addition quantity. This avoids in particular that the water vapor present in the tube with a negative pressure of a few millibars is enclosed by the flushing gas as it enters and then experiences a pressure rise that goes beyond the saturation point to normal pressure, the previously evaporated water being deposited on the inner walls of the tube.
• a such an effect is inevitable if the evacuation and flushing is carried out from one end of a pipe section, the flushing gas leading to an inclusion of the water vapor even with slow input and trapping the residual water which remains in the pipe.
• a similar effect could also arise if flushing gas is added unthrottled from an end of the pipeline remote from the evacuation point, so that the water vapor experiences a pressure increase on the way to the evacuation point.
• a throttling or flow metering of the flushing gas stream must be maintained until the flushing gas stream reaches the evacuation point or whether the metering can soon be released to a greater or lesser extent depends on the flow properties of the line.
• the introduction of the purge gas can be released after an initial throttling, i.e. unthrottled and with an inlet pressure increased to or even above normal pressure.
• the flow resistance of the line acts as a sufficient throttle to maintain a pressure below the saturation limit in the boundary area to the extracted water vapor. The pressure rising further back does not reach the front of the purge gas.
• pipe drying is preferably carried out in such a way that the evacuation takes place at one end of a closed pipe section and the flushing gas is input at the other end.
• Appropriate handling at several points for example from the point of view of shorter throughput times and thus shorter working hours, is of course possible, for example, evacuation and flooding points can alternately be provided along a pipeline section.
• Dry purge air is let in at the end of the pipeline section opposite the evacuation point, a supercritical nozzle being switched on in the inlet, which limits the purge gas flow to 50 Nm 3 / h, so that the purge gas flow remains behind the suction power of the vacuum pump in terms of its molar flow rate.
• the vacuum pump on the other side of the pipe section remains switched on. After purging air emerges at the evacuation point, the vacuum pump is switched off and the nozzle is removed from the purging air inlet in order to accelerate the further flooding of the pipeline to normal pressure. Additional flooding from the evacuation point is then uncritically possible after the water vapor has been removed from the line.
• a pipe section as in Example I is emptied and evacuated after the pressure water test, as before wrote.
• the flooding of the line with dried purge air takes place in a multi-stage process, which was simulated or calculated beforehand taking into account the flow resistance of the line, the suction power of the vacuum pump and the flow properties of the enclosed gases on a digital computer using the finite element method to ensure that with a gradual release of the purge air supply even in the end part of the extracted water vapor volume, directly in front of the trailing purge air column, there is no pressure increase beyond the saturation pressure and thus recondensation.
• a purge air is first entered through a supercritical nozzle as in Example I. After a predetermined time interval, a bypass with a second, same supercritical nozzle is opened. After further predetermined time intervals, a third and a fourth bypass of the appropriate type are opened. It goes without saying that a single nozzle with a plurality of openings corresponding to a supercritical nozzle can also be used, which are opened one after the other.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Drying Of Solid Materials (AREA)
• Pipeline Systems (AREA)
• Rigid Pipes And Flexible Pipes (AREA)

Priority Applications (1)

Applications Claiming Priority (2)

Publications (2)

Family

ID=6200855

Family Applications (1)

Country Status (7)

Cited By (2)

Families Citing this family (2)

Citations (3)

Family Cites Families (2)

• 1983
  • 1983-06-07 DE DE3320512A patent/DE3320512A1/de not_active Withdrawn
• 1984
  • 1984-05-29 CA CA000455328A patent/CA1252287A/fr not_active Expired
  • 1984-05-30 AT AT84106164T patent/ATE22489T1/de active
  • 1984-05-30 DE DE8484106164T patent/DE3460811D1/de not_active Expired
  • 1984-05-30 EP EP84106164A patent/EP0130372B1/fr not_active Expired
  • 1984-05-31 AU AU28879/84A patent/AU560393B2/en not_active Ceased
  • 1984-06-06 NO NO842284A patent/NO157992C/no unknown
  • 1984-06-07 US US06/618,098 patent/US4538359A/en not_active Expired - Fee Related

Patent Citations (3)

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