Process for manufacturing sodium hydrosulfide solution

Claim 1

A CONTINUOUS PROCESS FOR THE PRODUCTION OF SODIUM HYDROSULFIDE SOLUTION WHICH COMPRISES CONTACTING, IN AN ABSORPTION ZONE, A FRESH AQUEOUS ABSORBENT WITH A GASEOUS MIXTURE CONSISTING ESSENTIALLY OF NORMALLY GASEOUS C2 AND C3 HYDROCARBONS AND CONTAINING HYDROGEN SULFIDE IN AN AMOUNT BETWEEM ABOUT 0.25-20 PER CENT BY WEIGHT, IN THE RATIO OF ABOUT 1-25 GALLONS OF ABSORBENT PER 1000 CUBIC FEET OF GASEOUS MIXTURE AT OPERATING CONDITIONS, SAID ABSORBENT CONTAINING NOT LESS THAN 25 PER CENT BY WEIGHT OF SOLUTES CONSISTING ESSENTIALLY OF SODIUM HYDROSULFIDE AND SODIUM SULFIDE, SAID SODIUM SULFIDE BEING PRESENT IN AN AMOUNT INSUFFICIENT TO CAUSE INCIPIENT PRECIPITATION UNDER OPERATING CONDITIONS, AT A TEMPERATURE BETWEEN ABOUT 100-150.F. TO PRODUCE A SPENT ABSORBENT CONTAINING NOT LESS THAN 25 PERCENT BY WEIGHT OF SODIUM HYDROSULFIDE, WITHDRAWING A MINOR PORTION OF THE ABSORBENT FROM THE ABSORPTION ZONE AFTER SAID CONTRACTING, SAID WITHDRAW ABSORBENT CONTAINING NOT LESS THAN 25 PER CENT BY WEIGHT OF SODIUM HYDROSULFIDE, ADMITTING THE REMAINING PROPORTION OF THE ABSORBENT WITH AN AMOUNT OF AQUEOUS SODIUM HYDROXIDE SOLUTION INSUFFICIENT TO CAUSE PRECIPITATION OF SODIUM SULFIDE AT SAID TEMPERATURE TO PRODUCE THE AFOREMENTION FRESH ABSORBENT, RE CYCLING AND FRESH ABSORBENT TO SAID ABSORPTION ZONE WHEREIN IT IS CONTACTED WITH ADDITIONAL AMOUNTS OF SAID GASEOUS MIXTURE IN THE AFOREMENTIONED RATIO, CONTINUOUSLY REPEATING THE FOREGOING CYCLE EMPLOYING A RECYCLE RATIO OF NOT LESS THAN ABOUT 4:1 WHILE CONTINUOUSLY WITHDRAWING FROM SAID ABSORPTION ZONE A MINOR PORTION OF THE SPENT ABSORBENT SUBSEQUENT TO THE CONTACTING OF THE FRESH ABSORBENT WITH HYDROGEN SULFIDE THEREBY CONTINUOUSLY PRODUCING A CONCENTRATED SOLUTION CONTAINING NOT LESS THAN 25 PER CENT BY WEIGHT OF SODIUM HYDROSULFIDE AND A GASEOUS EFFLUENT CONSISTING ESSENTIALLY OF NORMALLY GASEOUS C2 AND C3 HYDROCARBONS AND CONTAINING NOT MORE THAN 300 GRAINS OF HYDROGEN SULFIDE PER 100 CUBIC FEET OF GASEOUS EFFLUENT AT STANDARD CONDITIONS.