Questions regarding permutation
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After the low-temperature water transportation process, nitrogen is used to displace the water after it has been drained; so when is it considered that the displacement is complete? What is the standard for determining a good replacement?
When [H2O] ≤ 1.0% and ≤ 0.5%, the drying and displacement are satisfactory
As already mentioned in a post: the oxygen content is less than 0.5%； The nitrogen dew point temperature is about -30 degrees!
Have the analysis team take a sample on-site (at a location far from the source of gas) to conduct testing, mainly to measure the oxygen content
After washing, it is necessary to dry the material first; drainage is carried out at the lowest points. Generally, when the gas discharged feels dry to the touch, it can be preliminarily determined that the drying process is complete! The standard for qualifying a replacement is: the oxygen content in the replaced gas must be less than 0.5%!
At this time, the displacement is primarily aimed at removing water from the system; the saturation point of N2 at –30°C is analyzed to determine whether any water will precipitate. If no water precipitates, the displacement is considered successful
The standard for qualifying a replacement is: the oxygen content in the replaced gas must be less than 0.5%!
Find an analysis point at the displaced far point for analysis~! The oxygen content ranges from 0.2 to 0.5; the values vary among different plants depending on the degree of equipment corrosion
In fact, the system should have already been purged with N2 before the water transfer process; the purification after the water transfer is merely intended to ensure the dryness of the system and thereby reduce the thermal load on the methanol-water separation tower； In the winters of the north, extra attention should be paid to ice damage to equipment.
The system can be dried and purged simultaneously, which saves nitrogen
Nitrogen displacement and drying are carried out by introducing nitrogen through the nitrogen pipelines of their respective towers, with the pressure controlled at 0.45 MPa. An intermittent pressurization and repeated venting method is employed. The acceptable criteria for dryness at the sampling port are: an oxygen content of less than or equal to 0.2%, and no leakage at temperatures below -30 degrees.
Nitrogen is filled into the system after water transport to dry the adsorbed water on the inner walls of the system. The standard for qualifying as a substitute is an oxygen content of less than 0.5%, and a water content in methanol of less than 1%
It’s mainly the oxygen content, to prevent any dangers