Appearance and tightness test are the basis. It is required to check whether there is deformation and crack on the shell of the cold box, and whether the sealing part leaks air. Meanwhile, observe whether the surface frosts evenly, and abnormal frosting may indicate internal leakage. In addition, for the cold box filled with perlite, check the sand leakage to ensure the thermal insulation performance.
Process parameter monitoring is essential. The temperature, pressure, liquid level and other parameters in the cold box are monitored by the sensor in real time, and the deviation is analyzed by comparing the design value. For example, abnormal drop of liquid oxygen level of main cooling system may indicate leakage of liquid nitrogen pipeline, which shall be checked in time.
Internal structure inspection is indispensable. Use an endoscope or disassemble part of the structure to check whether the support frame and guide bracket in the cold box are stable and whether the pipeline and equipment are firmly connected to avoid looseness caused by vibration during operation.
NDT and material re-inspection to improve safety. Radiographic testing, ultrasonic testing and other methods shall be adopted to carry out non-destructive testing on key welds to ensure welding quality; At the same time, recheck the materials used in the cold box to confirm that they meet the design requirements and prevent accidents caused by material defects.
Through the above inspection, the status of the cold box can be comprehensively evaluated, and hidden dangers can be found and handled in time to ensure the long-term stable operation of the air separation equipment.
