Large air separation FAQ

What is the principle of overflow bucket of sieve tray column in air separation plant? What's the effect?

Types of molecular sieves

What are the characteristics of structured packed column and sieve tray column in air separation plant?

Switching time of molecular sieve purification

What is the "three Simultaneities" of safety production

What does "three level safety education" mean

What's the reason for using two-stage distillation column in air separation column?

Sieve tray column

Superheated steam

The air separation cold box is filled with insulation material, generally pearlite, and the pearlite particles are filled with air. After the operation of the air separation unit, the temperature of the insulation material and the air will decrease, and the volume will decrease. At this time, if the cold box is well sealed, negative pressure will be formed in the cold box, and the cold box may be compressed under the effect of internal and external pressure difference. If the cold box is not well sealed, the moisture outside the cold box will enter the cold box, making the insulation material damp, and the cold loss of the unit will be greatly increased. In order to prevent the cold box from being compressed and the thermal insulation material from becoming damp, dry nitrogen or crude nitrogen is usually filled into the cold box after the unit is running to keep the cold box at slightly positive pressure.

Pressure test before valve installation 1. In the warranty period, those with the certification and the sealing surface is intact can no longer conduct the strength test alone, but only the air tightness test can be taken before installation. 2. Within the warranty period, it has the certificate, and its sealing surface has defects such as corrosion and damage. After treatment, it must carry out the air tightness test. 3. Outside the warranty period, those with certification and intact sealing surface shall be subject to air tightness test before installation. 4. For valves that need to be degreased and disassembled on site, air tightness test shall be conducted separately before installation. 5. The safety valve shall be sent to the local quality inspection department of the project for verification before the end of installation and commissioning.

The most important index of radiographic quality is the sensitivity of radiography, which is the size of the smallest defect along the direction of ray penetration that can be found on the negative plate quantitatively. Natural defects’ size are hard to be sure. It is obvious that it is unrealistic to use natural defects to evaluate the sensitivity of radiography. Therefore, in order to facilitate the evaluation of photographic quality, it is often used to monitor the image quali...