Method for obtaining an air product in an air separation plant and air separation plant

Air separation plant for obtaining an air product, said air separation plant comprising:

• a distillation column system and a tank system having a first tank and a second tank,
• means for withdrawing a cryogenic liquid from the distillation column system and means for introducing at least part of the cryogenic liquid into the tank system to store at least part of the cryogenic liquid in the tank system, wherein said means for introducing includes means for supplying the cryogenic liquid to the first tank and not to the second tank during a first period, and for supplying the cryogenic liquid to the second tank and not to the first tank during a second period, and
• means for withdrawing the cryogenic liquid from the second tank and not from the first tank during the first period, and for withdrawing the cryogenic liquid from the first tank and not from the second tank during the second period,
• said tank system further comprising a third tank, and means for transferring the cryogenic liquid which is withdrawn from the second tank during the first period, and withdrawn from the first tank during the second period, at least temporarily and at least partially unheated into the third tank,
• means for withdrawing from the third tank the cryogenic liquid in the liquid state from the third tank to provide the air product, and
• means for vaporizing the cryogenic liquid or converting the cryogenic liquid from a the liquid to a supercritical state to thereby produce the air product, and means for discharging the air product from the air separation plant, and/or means for introducing the cryogenic liquid in the liquid state withdrawn from the third tank into a fourth tanks to store the cryogenic liquid in the liquid state in said fourth tank.

A method for obtaining an air product using an air separation plant having a distillation column system and a tank system with a first tank and a second tank, said method comprising:

• withdrawing a cryogenic liquid from the distillation column system, storing the cryogenic liquid at least in part in the tank system, and using the cryogenic liquid at least in part as the air product,
• wherein the cryogenic liquid is supplied to the first tank and not to the second tank during a first period, and is supplied to the second tank and not to the first tank during a second period, and wherein the cryogenic liquid is withdrawn from the second tank and not from the first tank during the first period, and is withdrawn from the first tank and not from the second tank during the second period,
• wherein a purity of the cryogenic liquid, which is supplied to the first tank during the first period, is determined in the first tank and a purity of the cryogenic liquid, which is supplied to the second tank during the second period, is determined in the second tank,
• wherein the tank system comprises an additional third tank, and if the cryogenic liquid in the second tank has a purity corresponding to a setpoint, cryogenic liquid withdrawn from the second tank during the first period is transferred, at least partially, unheated into the third tank, and if the cryogenic liquid in the first tank has a purity corresponding to the setpoint, cryogenic liquid withdrawn from the first tank during the second period, is transferred, at least partially, unheated into the third tank,
• wherein, if cryogenic liquid is in stored in the third tank, the air product is provided at least in part by using at least part of the cryogenic liquid transferred, unheated, into the third tank, and
• cryogenic liquid from the third tank used for providing the air product is withdrawn from the third tank in the liquid state, vaporized or converted from the liquid to the supercritical state, and discharged from the air separation plant, and/or cryogenic liquid from the third tank used for providing the air product is withdrawn from the third tank in the liquid state and stored in the liquid state in a fourth tank.