Purification of coal distillation gases

Claim 1

A PROCESS OF REMOVING HYDROGEN SULFIDE FROM A COAL DISTILLATION GAS CONTAINING THE SAME AND ALSO CONTAINING WATER VAPOR AND A HIGH PERCENTAGE OF AMMONIA, COMPRISING THE STEPS OF COMPRESSING SAID COAL DISTILLATION GAS TO A PREDETERMINED PRESSURE GREATER THAN ATMOSPHERIC PRESSURE; COOLING SAID COMPRESSED GAS SO AS TO CONDENSE SAID WATER VAPOR AND FORM AN AQUEOUS CONDENSATE HAVING A HIGH CONCENTRATION OF AMMONIA; SCRUBBING THE COMPRESSED GAS WITH A FIRST AQUEOUS AMMONIA SOLUTION HAVING A PREDETERMINED AMMONIA CONCENTRATION WHICH IS LOWER THAN THE AMMONIA CONCENTRATION OF SAID AQUEOUS CONDENSATE, THEREBY CAUSING ABSORPTIO N OF HYDROGEN SULFIDE CONTAINED IN SAID GAS BY SAID FIRST AQUEOUS AMMONIA SOLUTION AND CAUSING ALSO DILUTION OF SAID FIRST AQUEOUS AMMONIA SOLUTION DUE TO LOSS OF A PORTION OF THE AMMONIA THEREFROM; SEPARATING FROM SAID SCRUBBED GAS THE THUS OBTAINED DILUTED AQUEOUS AMMONIA SOLUTION CONTAINING ABSORBED HYDROGEN SULFIDE; WITHDRAWING FROM SAID DILUTED AQUEOUS AMMONIA SOLUTION A PORTION THEREOF AND ADDING TO SAID DILUTED AQUEOUS AMMONIA SOLUTION AN AMOUNT OF SAID AQUEOUS CONDENSATE, SAID WITHDRAWN PORTION OF SAID DILUTED AQUEOUS AMMONIA SOLUTION AND SAID ADDED AMOUNT OF SAID AQUEOUS CONDENSATE BEING SO ADJUSTED THAT THE RESULTING MIXTURE HAS THE SAME VOLUME AND AMMONIA CONCENTRATION AS SAID FIRST AQUEOUS AMMONIA SOLUTION; DISTILLING-OFF SAID HYDROGEN SULFIDE FROM THE THUS FORMED MIXTURE UNDER SUPER ATMOSPHERIC PRESSURE, THEREBY RECOVERING A PURIFIED AQUEOUS AMMONIA SOLUTION HAVING SAID PREDETERMINED AMMONIA CONCENTRATION; AND RECYCLING SAID PURIFIED AQUEOUS AMMONIA SOLUTION INTO ADDITIONAL COMPRESSED GAS FOR THE SCRUBBING OF THE ADDITIONAL COMPRESSED GAS.