Vaporization-condensation apparatus for air distillation double column, and air distillation equipment including such apparatus

Abstract

The air distillation double column (1,2) includes an apparatus for vaporizing oxygen and condensing nitrogen which comprises on one hand a running type main heat exchanger (7) which is partially immersed during stoppage of the equipment and on the other hand an auxiliary heat exchanger (20) which alone is responsible for liquid vaporization when the equipment is restarted.

We claim: 
     
       1. Apparatus for vaporizing oxygen and condensing nitrogen for air distillation equipment of the double column type having a low pressure column containing a vat and a mean pressure column and comprising at least a main heat exchanger disposed in the vat of the low pressure column, said exchanger being of the running type and including oxygen ducts .[.and nitrogen ducts.]., means for causing oxygen to run in excess in said .Iadd.oxygen .Iaddend.ducts, means for withdrawing total vaporized oxygen and excess liquid oxygen through a lower end of said .Iadd.oxygen .Iaddend.ducts.Iadd., nitrogen ducts .Iaddend.in indirect heat exchange relationship with the oxygen ducts, means for feeding nitrogen gas originating from the mean pressure column to the nitrogen ducts and means for returning condensed nitrogen to the mean pressure column, wherein the main heat exchanger is mounted so as to be at least partially immersed during a stoppage in the operation of the air distillation equipment, the improvement comprising at least an auxiliary heat exchanger for ensuring, substantially by itself, liquid vaporization when the main exchanger is at least partially immersed. 
     
     
       2. The improvement according to claim 1, wherein the auxiliary exchanger is of the running type containing oxygen ducts and nitrogen ducts in indirect heat exchange relationship with the oxygen ducts, means for feeding the nitrogen ducts with nitrogen gas originating from the mean pressure column, means for supplying excess liquid oxygen from the auxiliary exchanger to the main heat exchanger, means to return condensed nitrogen in the mean pressure column, means for returning liquid oxygen contained in the vat of the low pressure column to the top of the oxygen ducts of the auxiliary exchanger and means for returning liquid oxygen from the lower end of the auxiliary exchanger to the top of the oxygen ducts of the main exchanger. 
     
     
       3. The improvement according to claim 2, wherein the auxiliary exchanger is entirely located above a maximum level of the liquid oxygen in the vat of the low pressure column. 
     
     
       4. The improvement according to claim 3, wherein the auxiliary exchanger is entirely mounted above the top of the main exchanger. 
     
     
       5. The improvement according to claim 4, wherein the auxiliary exchanger is mounted in the low pressure column above the main exchanger. 
     
     
       6. The improvement according to claim 2, wherein the auxiliary exchanger is mounted outside the low pressure column. 
     
     
       7. The improvement according to claim 1, wherein the auxiliary exchanger is an exchanger of the same type as the main exchanger and is mounted at substantially the same level as the main exchanger, the top of the oxygen ducts of the auxiliary exchanger being covered with a sealed feeding box supplied exclusively through a duct for moving liquid contained in said vat upwardly to said auxiliary exchanger. 
     
     
       8. The improvement according to claim 1, wherein the auxiliary heat exchanger is a bath type exchanger mounted below the maim exchanger in the vat of the low pressure column. 
     
     
       9. Equipment for air distillation of the double column type having a low pressure column and a mean pressure column and comprising at least a main heat exchanger disposed in the low pressure column, said exchanger being of the running type and including oxygen ducts for causing oxygen to run in excess in said ducts, means for withdrawing total vaporized oxygen and excess liquid oxygen through an end of said ducts.Iadd., nitrogen ducts .Iaddend.in indirect heat exchange relationship with the oxygen ducts, means for feeding nitrogen gas from the mean pressure column to .Iadd.said .Iaddend.nitrogen ducts, and means for returning condensed nitrogen to said mean pressure column, wherein said main heat exchanger is mounted so as to be at least partially immersed during a stoppage in the operation of the double column, the improvement comprising at least an auxiliary heat exchanger for providing, by itself, liquid vaporization when said main exchanger is at least partially immersed in said liquid oxygen.