Process for preparing hydrogen-nitrogen mixtures from coke oven gas

Claim 1

IN A PROCESS FOR PREPARING HYDROGEN-NITROGEN MIXTURES FROM COKE OVEN GAS BY COOLING SAID GAS UNDER PRESSURE TO CONDENSE LOW VOLATILE CONSITUENTS AND THEREAFTER WASHING THE RESULTING COLD GASEOUS RESIDUE UNDER PRESSURE BY COUNTER-CURRENTLY CONTACTING THE SAME WITH LIQUID NITROGEN TO REMOVE METHANE AND CARBON MONOXIDE THEREFROM, THE IMPROVEMENT WHICH COMPRISES INITIALLY WASHING SAID COLD GASEOUS RESIDUE BY PASSING SAME UPWARDLY THROUGH A FIRST WASHING ZONE WHEREIN SAID RESIDUE IS WASHED BY COUNTER-CURRENT CONTACT WITH LIQUID NITROGEN, THEN PASSING THE THUS THREADED GASEOUS RESIDUE UPWARDLY THROUGH AN INTERMEDIATE CONDENSING ZONE WHEREIN SAID RESIDUE IS INDIRECTLY COOLED WITH BOILING NITROGEN UNDER A CONSTANT PRESSURE PREFERABLY SLIGHTLY HIGHER THAN ATMOSPHERIC AND A CONDENSATE OF NITROGEN IS OBTAINED FROM SAID RESIDUE, THEREAFTER FURTHER WASHING SAID GASEOUS RESIDUE BY PASSING SAME UPWARDLY THROUGH A SECOND WASHING ZONE IN COUNTER-CURRENT CONTACT WITH LIQUID NITROGEN, THE HEIGHT OF SAID FIRST WASHING ZONE BEING SUBSTANTIALLY LESS THAN THAT OF SAID SECOND WASHING ZONE, COLLECTING LIQUID WASHING NITROGEN CONTAMINATED WITH CARBON MONOXIDE FROM SAID SECOND WASHING ZONE AND UTILIZING THE COOLED NITROGEN AND THE CONDENSATE FROM SAID CONDENSING ZONE AS THE LIQUID NITROGEN FOR WASHING SAID GASEOUS RESIDUE IN SAID FIRST WASHING ZONE.