Method and device for separation at cryogenic temperature

A method for separating air at a cryogenic temperature, the method comprising the steps of:

• a) exchanging heat directly or indirectly between a first cold source at a first cryogenic temperature and a first hot source at a second cryogenic temperature using at least one first heat pump that uses the magnetocaloric effect, thus providing at least some of the separation energy, wherein the at least one first heat pump is referred to as a separation heat pump;
• and
• b) exchanging heat directly or indirectly between a second cold source at a first cryogenic temperature and a second hot source at a temperature higher than the first temperature using at least a second heat pump that uses the magnetocaloric effect, thereby providing at least some of the cold needed to maintain the refrigeration balance of the method, the separation taking place in a single column or a set of columns, the pressure of the single column or of the columns of the set being below 2 bara,
• wherein the first cold source and the first hot source are directly or indirectly thermally connected to the single column or to one column of the set,
• wherein the second heat pump is referred to as a refrigeration balance heat pump,
• wherein the first and second heat pumps use the magnetocaloric effect and in that the second cold source is selected from the group consisting of air intended to be separated in the single column or the set of columns, of a fluid coming from the single column or from the set of columns, and combinations thereof.

A device for separating air using a method of separation at cryogenic temperature comprising:

• a single column or a set of columns in which cryogenic separation takes place;
• means for sending a mixture of air gases to the column or a column of the set;
• means for withdrawing at least one fluid enriched in a component of the mixture from the column;
• at least a first heat pump, using the magnetocaloric effect, configured to heat directly or indirectly between a cold source at cryogenic temperature and a hot source at cryogenic temperature, thereby supplying at least part of the separation energy, wherein the first heat pump is referred to as the separation heat pump;
• and
• at least a second heat pump, using the magnetocaloric effect, referred to as the refrigeration balance heat pump, wherein the second heat pump is configured to exchange heat directly or indirectly between a cold source at a first cryogenic temperature consisting of the air intended to be separated in the single column or the set of columns and a hot source at a temperature higher than the first temperature, thus supplying at least a portion of the cold needed to maintain a refrigeration balance when in operation,
• wherein the pressure of the single column or of the columns of the set is below 2 bara, so that the column is or the columns are connected to the atmosphere via at least one pipe that comprises an absence of an expansion means,
• wherein the first cold source and the first hot source are directly or indirectly thermally connected to the single column or to a column of the set.