Biogas purification cases

The start-up and operation of liquid air separation plants requires the operator to be familiar with the performance and operation of the systems, machines and equipment in the liquid air separation plants, to be familiar with the process flow diagram of the liquid air separation plants, and to master the operation rules and operating characteristics of the liquid air separation plants. In order to ensure the purity of the product, the operator must be able to improve the quality of the product ...

What is the reason why the purity of the lower column is the basis for the purity adjustment of the upper column product?