Thermal destruction of halocarbons

Abstract

A downcomer used to direct hot flue gases from oxidative combusion of halocarbons into an aqueous medium in a quench tank has improved corrosion resistance when made of rhenuim, molybdenum, or an alloy containing at least 50 wt % molybdenum and having a corrosion rate not exceeding 0.254 mm/yr.

I claim: 
     
       1. An apparatus for converting gaseous hydrogen halides contained in hot flue gas to an aqueous solution of said hydrogen halides, comprising: (a) downflow cylinder means having an upper inlet for receiving said flue gas and a lower outlet,   (b) means for flowing an aqueous medium along the interior surface of said cylinder means, said interior surface of said downflow cylinder means comprising rhenium, molybdenum, or a metal of at least 50% by weight of molybdenum, and having a corrosion rate not exceeding 0.254 mm/year. and,   (c) means for quenching and containing an aqueous medium positioned in communication with said outlet for receiving said flue gas after passage through said downflow cylinder means and thereby cooling said flue gas and forming said aqueous solution of the said hydrogen halide therein.   
     
     
       2. The apparatus of claim 1 and a means for withdrawing said aqueous solution of hydrogen halides from said containing means at a rate such that the concentration of said hydrogen halides in solution therein is at least 10% by weight. 
     
     
       3. The apparatus of claim 1 and a means for supplying a portion of said aqueous medium from said containing means to said flowing means. 
     
     
       4. A process comprising: (a) oxidatively combusting a halocarbon in a combustion zone to form a flue gas having a temperature of at least 1000° C., the combustion of said halocarbon converting said halocarbon to gaseous hydrogen halides present in said flue gas,   (b) passing said flue gas through a downflow cylinder communicating between said combustion zone and a pool of aqueous medium while cooling the interior surface of said cylinder with aqueous medium, said interior surface comprising rhenium, molybdenum, or a metal of at least 50% by weight molybdenum and having a corrosion rate not exceeding 0.254 mm/year,   (c) collecting an aqueous solution of said gaseous hydrogen halide in said pool of aqueous medium.   
     
     
       5. The process of claim 4 and additionally, withdrawing aqueous medium from said pool at a rate at which the concentration of said hydrogen halides therein is at least 10% by weight. 
     
     
       6. The process of claim 5 wherein said hydrogen halides include hydrogen fluoride. 
     
     
       7. The process of claim 6 wherein said interior surface is molybdenum and said concentration of said hydrogen halides in said aqueous medium is up to 30% by weight. 
     
     
       8. The process of claim 6 wherein said interior surface is an alloy of molybdenum and rhenium and the concentration of said hydrogen halides in said aqueous medium is up to 50% by weight. 
     
     
       9. The process of claim 6 wherein said interior surface is rhenium or an alloy of molybdenum, rhenium and tungsten and the concentration of hydrogen halides in said aqueous medium is greater than 50% by weight. 
     
     
       10. The process of claim 6 wherein said interior surface is a metal selected from the group consisting of rhenium, molybdenum, alloy of molybdenum with 5% to 50% rhenium by weight, and alloy of molybdenum with rhenium and 10% to 20% tungsten by weight.