Operation and maintenance of air separation unit

In the air separation plant, the main heat exchanger is the key equipment to ensure the performance of the whole set of equipment. The function of the main heat exchanger in the molecular sieve pre purification process air separation equipment is to ensure the temperature difference at the hot end to be kept at the design value by recovering the cold quantity of the backflow gas, provide sufficient expander gas to expander, make up for the cold quantity loss of the equipment, and provide the raw gas under the design condition for the lower tower.

The expansion air volume entering the upper tower increases, and the reflux ratio of the distillation section decreases correspondingly. In order to achieve the required purity of nitrogen products, more tower plates need to be set. When the reflux ratio is reduced to countless Tower plates needed to be set to make the purity of nitrogen reach the required value, then the reflux ratio is called the minimum reflux ratio. The expansion air volume entering the upper tower is first limited by the minimum reflux ratio. The closer the reflux ratio is to the minimum reflux ratio, the faster the number of tower plates needed to ensure the product purity increases, which will lead to the increase of investment, the increase of tower plate resistance, the increase of Operation pressure and the increase of energy consumption. Therefore, the reflux ratio after the inflated air enters the tower should be larger than the minimum reflux ratio. When the purity of nitrogen is required to be low, the...