A process for the separation of air comprising: a) compressing the air; b) cooling the compressed air to produce cooled compressed air and further cooling the cooled compressed air to produce further cooled air at an intermediate temperature; c) cooling the further cooled air by an additional cooling process to a cryogenic temperature; and d) sending the air at the cryogenic temperature to a distillation column of a cryogenic distillation unit, characterised in that step b) comprising: i) providing at least one elongated vessel having a substantially vertical orientation, wherein said elongated vessel comprises: • a first end and a second end; • a first compartment for indirect heat exchange between the compressed air and at least one cooling stream to produce the cooled compressed air; • a second compartment for direct contact between said cooled compressed air and a liquid stream to produce the further cooled air; and • a barrier which separates said first and second compartments, and when in use, allows for the upward passage of air, but prevents the downward passage of liquid; ii) introducing the compressed air into said first compartment proximate to said first end, removing said further cooled air from said second compartment proximate to said second end; iii) introducing at least one cooling stream into said first compartment removing said warmed at least one cooling stream from said first compartment; and iv) introducing a liquid stream into said second compartment proximate to said second end, and removing said warmed liquid stream from said second compartment proximate to said barrier. a) compressing the air; b) cooling the compressed air to produce cooled compressed air and further cooling the cooled compressed air to produce further cooled air at an intermediate temperature; c) cooling the further cooled air by an additional cooling process to a cryogenic temperature; and d) sending the air at the cryogenic temperature to a distillation column of a cryogenic distillation unit, characterised in that step b) comprising: i) providing at least one elongated vessel having a substantially vertical orientation, wherein said elongated vessel comprises: • a first end and a second end; • a first compartment for indirect heat exchange between the compressed air and at least one cooling stream to produce the cooled compressed air; • a second compartment for direct contact between said cooled compressed air and a liquid stream to produce the further cooled air; and • a barrier which separates said first and second compartments, and when in use, allows for the upward passage of air, but prevents the downward passage of liquid; ii) introducing the compressed air into said first compartment proximate to said first end, removing said further cooled air from said second compartment proximate to said second end; iii) introducing at least one cooling stream into said first compartment removing said warmed at least one cooling stream from said first compartment; and iv) introducing a liquid stream into said second compartment proximate to said second end, and removing said warmed liquid stream from said second compartment proximate to said barrier. i) providing at least one elongated vessel having a substantially vertical orientation, wherein said elongated vessel comprises: • a first end and a second end; • a first compartment for indirect heat exchange between the compressed air and at least one cooling stream to produce the cooled compressed air; • a second compartment for direct contact between said cooled compressed air and a liquid stream to produce the further cooled air; and • a barrier which separates said first and second compartments, and when in use, allows for the upward passage of air, but prevents the downward passage of liquid; • a first end and a second end; • a first compartment for indirect heat exchange between the compressed air and at least one cooling stream to produce the cooled compressed air; • a second compartment for direct contact between said cooled compressed air and a liquid stream to produce the further cooled air; and • a barrier which separates said first and second compartments, and when in use, allows for the upward passage of air, but prevents the downward passage of liquid; ii) introducing the compressed air into said first compartment proximate to said first end, removing said further cooled air from said second compartment proximate to said second end; iii) introducing at least one cooling stream into said first compartment removing said warmed at least one cooling stream from said first compartment; and iv) introducing a liquid stream into said second compartment proximate to said second end, and removing said warmed liquid stream from said second compartment proximate to said barrier.