Maintenance of large air separation unit

There are mainly the following factors that affect the output of oxygen: 1) insufficient processing air volume. The reasons for the shortage of air volume include: ① the ambient temperature is too high; ② the atmospheric pressure is too low; ③ the air suction filter is blocked; ④ the low voltage or the frequency of the power grid will reduce the rotating speed; ⑤ the cooling effect of intermediate cooler is not good; ⑥ internal leakage exists between levels; ⑦ air leakage of valve and pipeline, and leakage of automatic valve or switching valve; ⑧ for the purification process of molecular sieve, it may be the air leakage of switching butterfly valve. 2) the average purity of nitrogen is too low. The reasons are: ① the efficiency of the distillation column is reduced; ② the expansion air volume is too large due to too much cold loss; ③ the purity of liquid nitrogen is too low and the liquid nitrogen volume is too large; ④ the liquid nitrogen volume is too small; ⑤ leakage of liquid ai...

The air contains 0.932% argon. When 99.6% oxygen is to be produced from the upper tower, 1.05% argon must be contained in the nitrogen discharge. From the perspective of separation process, the distillation section of the upper tower (below the liquid inlet) is basically oxygen-argon separation, while in the distillation section (above the liquid inlet) then it is basically nitrogen-oxygen (argon) separation. The boiling point of argon and oxygen is relatively close (the boiling point of oxygen is-182.97 ℃ at 0.1013MPa, and the boiling point of argon is-185.7 ℃), so it is relatively difficult to separate. In the distillation section, such a situation often occurs. In the process of nitrogen-oxygen separation, the oxygen component is not separated clean, and the argon component basically escapes together with the oxygen component in the nitrogen discharge, reduce the purity of nitrogen. If it is required to produce high purity nitrogen, the oxygen component should be completely separ...