After the production overhaul was completed, the molecular sieve was activated, and the bare cold leak detection was conducted successfully. Once the bare cooling process was finished, both expanders were shut down, and the entire tower was subjected to heating. Following the completion of the heating phase, all internal and external valves were closed, the system was pressurized, the maintenance shelves were removed, the cold box foundation was cleaned and dried, and then filled with perlite sand. After the sand was loaded, the air compressor was started to supply air to the air separation unit. The product specifications and all operational parameters met or exceeded the design requirements, and the issue of ice formation outside the main cold box was completely resolved.
From experience, it is crucial to ensure that leak detection is thoroughly carried out after installation or major overhauls of the air separation equipment. No blind spots should be left during this process. Leaks of low-temperature gas or liquid within the cold box are a primary cause of equipment failure. During installation and pressure testing, every joint and connection must be carefully inspected to ensure there are no leaks before the cold box is sealed and filled with sand. The pipeline layout inside the cold box should be designed reasonably, avoiding placing low-temperature equipment too close to the cold box walls. This is because the cold box plates are typically made of ordinary carbon steel, which can become brittle under prolonged exposure to low temperatures—leading to potential cracks in the cold box walls. Additionally, equipment should be repaired or replaced according to the scheduled maintenance plan. Minimizing temporary shutdowns helps reduce thermal expansion and contraction stresses that can affect the longevity of pipelines.
Every time the air separation equipment is heated, the perlite sand inside the cold box often thaws, while other parts remain at low temperature. If the perlite becomes wet or frozen, it can lead to deformation or damage of the pipes inside the tower. It’s important to add perlite sand in a timely manner. After extended operation, the perlite may settle and needs to be replenished regularly. The perlite inside the cold box must also be kept dry. During normal operation, the cold box should be filled with sufficient dry and clean nitrogen. During temporary shutdowns, the cold box should be connected to an external source to inflate it and maintain pressure. Proper sealing of the cold box is essential. The inlet and outlet process pipes should be resealed with sealant approximately every five years. The manhole seals on the top of the main and auxiliary cold boxes should be checked frequently to prevent rainwater from entering, and it's recommended to use waterproof cloth for added protection.
Kids Waist Bag,Men Waist Bag,Women Waist Bas,Sport Waist Bags
Ningbo FonFON Industry&Trade Co.,Ltd , https://www.nbfonfon.com