Distillation separation apparatus and method of cleaning a reboiler/condenser of the apparatus

Abstract

A distillation apparatus comprises a reboiler/condenser ( 30 ), cleanable in operation, being duplicated by another reboiler/condenser ( 40 ). The apparatus comprises neither means for stopping gas to be condensed from being sent to the condenser to be cleaned nor means for stopping vaporized liquid from being withdrawn from the condenser to be cleaned.

1 . Distillation apparatus comprising at least one column ( 10 ,  60 ) having at least two bath reboiler/condensers ( 30 ,  40 ) located outside the column, means ( 1 ) for sending a gas enriched with a more volatile component from the column to each of the reboiler/condensers through at least a first respective pipe, means ( 2 ) for sending a liquid enriched with a more volatile component from each of the reboiler/condensers to the column through at least a second respective pipe, means ( 3 ) for sending liquid enriched with a less volatile component to each of the reboiler/condensers through at least a third respective pipe, means ( 4 ) for withdrawing a gas enriched with a less volatile component from each of the reboiler/condensers through at least a fourth respective pipe, means ( 11 ) for sending a mixture comprising at least the more volatile component and the less volatile component to the column and means for withdrawing at least one fluid enriched with one of the components from the column, characterized in that, in order to allow one ( 30 ) of the reboiler/condensers to be cleaned, the apparatus comprises means ( 22 ) for stopping liquid enriched with the more volatile component from being sent to the column of the reboiler/condenser to be cleaned and means ( 23 ) for stopping the liquid enriched with the less volatile component from being sent to the reboiler/condenser to be cleaned and does not comprise means for stopping gas enriched with the less volatile component from being withdrawn from the reboiler/condenser to be cleaned and/or means for stopping gas enriched with the more volatile component from being sent from the column to the reboiler/condenser to be cleaned.  
     
     
         2 . Air separation apparatus according to  claim 1  comprising a medium-pressure column ( 10 ), a low-pressure column ( 20 ), at least two bath reboiler/condensers ( 30 ,  40 ) located outside the columns, means ( 1 ) for sending a gas enriched with nitrogen from the medium-pressure column to each of the reboiler/condensers through at least a first respective pipe, means ( 2 ) for sending a liquid enriched with nitrogen from each of the reboiler/condensers to the medium-pressure column through at least a second respective pipe, means ( 3 ) for sending liquid enriched with oxygen from the low-pressure column to each of the reboiler/condensers through at least a third respective pipe, means ( 4 ) for sending a gas enriched with oxygen from each of the reboiler/condensers to the low-pressure column through at least a fourth respective pipe, means ( 11 ) for sending air to the medium-pressure column and means for withdrawing at least one fluid from one of the columns as product and means ( 13 ) for sending a liquid enriched with oxygen from the medium-pressure column to the low-pressure column,  
       characterized in that, in order to allow one of the reboiler/condensers to be cleaned, the apparatus comprises means ( 22 ) for stopping liquid enriched with nitrogen from being sent to the medium-pressure column from the reboiler/condenser to be cleaned and means ( 23 ) for stopping liquid enriched with oxygen from being sent from the low-pressure column to the reboiler/condenser to be cleaned and does not comprise means for stopping gas enriched with oxygen from being sent to the low-pressure column from the reboiler/condenser to be cleaned and/or means for stopping gas enriched with nitrogen from being sent from the medium-pressure column to the reboiler/condenser to be cleaned.  
     
     
         3 . Air separation apparatus according to  claim 1 , comprising a column ( 60 ), at least two bath reboiler/condensers ( 30 ,  40 ) located outside the column, means ( 1 ) for sending a gas enriched with nitrogen from the column to each of the reboiler/condensers through at least a first respective pipe, means ( 2 ) for sending a liquid enriched with nitrogen from each of the reboiler/condensers to the column through at least a second respective pipe, means ( 3 ) for sending liquid enriched with oxygen from the column to each of the reboiler/condensers through at least a third respective pipe, means ( 4 ) for sending a gas enriched with oxygen from each of the reboiler/condensers into at least a fourth respective pipe, means ( 11 ) for sending air to the column and means for withdrawing at least one fluid from the column as product,  
       characterized in that, in order to allow one of the reboiler/condensers to be cleaned, the apparatus comprises means ( 22 ) for stopping liquid enriched with nitrogen from being sent to the column from the reboiler/condenser to be cleaned and means ( 23 ) for stopping liquid enriched with oxygen from being sent from the column to the reboiler/condenser to be cleaned and does not comprise means for stopping gas enriched with oxygen from being sent into the fourth pipe from the reboiler/condenser to be cleaned and/or means for stopping gas enriched with nitrogen from being sent from the medium-pressure column to the reboiler/condenser to be cleaned.  
     
     
         4 . Air separation apparatus according to  claim 1 , comprising a medium-pressure column ( 10 ), a low-pressure column ( 20 ), at least two bath reboiler/condensers ( 30 ,  40 ) located outside the columns, means for sending a gas enriched with nitrogen from the medium-pressure column to a reboiler/condenser ( 70 ) of the low-pressure column, means ( 1 ) for sending air to each of the reboiler/condensers through at least a first respective pipe, means ( 2 ) for sending at least partially condensed air from each of the reboiler/condensers to the medium-pressure column through at least a second respective pipe, means ( 3 ) for sending liquid enriched with oxygen from the low-pressure column to each of the reboiler/condensers through at least a third respective pipe, means ( 4 ) for sending a gas enriched with oxygen from each of the reboiler/condensers to the low-pressure column through at least a fourth respective pipe, means for sending air ( 11 ) to the medium-pressure column and means for withdrawing at least one fluid from one of the columns as product and means ( 13 ) for sending a liquid enriched with oxygen from the medium-pressure column to the low-pressure column,  
       characterized in that, in order to allow one of the reboiler/condensers to be cleaned, the apparatus comprises means ( 22 ) for stopping at least partially condensed air from being sent to the medium-pressure column from the reboiler/condenser to be cleaned and means ( 23 ) for stopping liquid enriched with oxygen from being sent from the low-pressure column to the reboiler/condenser to be cleaned and does not comprise means for stopping gas enriched with oxygen from being sent to the low-pressure column from the reboiler/condenser to be cleaned and/or means for stopping air from being sent to the reboiler/condenser to be cleaned.  
     
     
         5 . Apparatus according to one of claims  2 ,  3  and  4 , comprising means ( 15 ,  17 ) for sending a purge gas enriched with nitrogen, possibly air, into the second pipe of the reboiler/condenser to be cleaned and/or a purge gas enriched with oxygen into the third pipe of the reboiler/condenser to be cleaned.  
     
     
         6 . Apparatus according to one of claims  2 ,  3  and  4 , comprising venting means ( 16 ,  18 ) connected to the first and fourth pipes of the reboiler/condenser to be cleaned.  
     
     
         7 . Apparatus according to  claim 5  or  6 , in which the venting means and/or the means for sending purge gas comprise calibrated orifices.  
     
     
         8 . Apparatus according to  claim 6  or  7 , in which the venting means and/or the means for sending purge gas comprise automatic control valves.  
     
     
         9 . Apparatus according to one of the preceding claims, comprising an oxygen-enriched liquid purge pipe ( 7 ) connected to the bottom of the bath of each reboiler/condenser or to the third pipe.  
     
     
         10 . Apparatus according to one of the preceding claims, comprising a nitrogen-enriched liquid purge pipe ( 9 ) connected to the second pipe ( 2 ).  
     
     
         11 . Method for cleaning a reboiler/condenser of an apparatus according to one of the preceding claims, comprising the steps of: 
 i) isolating the second and third pipes of the reboiler/condenser to be cleaned by closing the access to the column(s);    ii) purging the liquid enriched with the less volatile component of the reboiler/condenser to be cleaned through a purge pipe;    iii) opening the vents of the first and/or fourth pipes and/or;    iv) sending nitrogen-enriched flushing gas into the second pipe; and/or    v) sending oxygen-enriched flushing gas into the third pipe.    
     
     
         12 . Method according to  claim 11 , in which the oxygen-enriched flushing gas has an oxygen content at least equal to that of the liquid in the bath of the reboiler/condenser in the operating state.  
     
     
         13 . Method according to  claim 11  or  12 , in which the nitrogen-enriched flushing gas has a nitrogen content at least equal to that of the nitrogen-enriched gas sent to the reboiler/condenser in the operating state.  
     
     
         14 . Method according to one of claims  11 ,  12  and  13 , in which the oxygen-enriched or nitrogen-enriched flushing gas undergoes a critical expansion before injection into the reboiler/condenser to be cleaned.  
     
     
         15 . Method according to  claims 11  to  14 , in which the flushing gases are at temperatures above the sublimation or vaporization temperature of the impurities present in the reboiler/condenser.  
     
     
         16 . Method according to  claims 11  to  15 , in which the liquid enriched with the more volatile component contained in the reboiler/condenser to be cleaned is purged after step i).  
     
     
         17 . Method according to  claims 11  to  16 , in which the rates of venting the first and fourth pipes are respectively greater than the rates of purging the second and third pipes.