Cryogenic air separation plant with two different operation modes

摘要

Whilst the plant produces gas, the passage of air through a cooling circuit has to be stopped, causing a loss of cooling which is compensated by stored liquid in order to maintain operating efficiency. Hence liquid oxygen (nitrogen or air) is stored in buffer tanks (79,80), compressed and used, in addition to the liquid from the rectification, during periods of high demand. In periods of low demand excess liquid is sent to the buffer tanks. In a combined process the additional cooling is supplied conventionally by air expanded in a turbine (309) driving a load such as a generator.Rectification is carried out in a double, or triple, column system. Air initially supplied by a compressor (30) is compressed further at a station (305) consisting of two compressors in parallel to increase the flexibility of the system.