Method and apparatus for conditioning flue gas with a mist of H.sub.2 SO.sub.4

Method of injecting an acid conditioning agent into a flue gas stream containing fly ash to be conditioned to enhance the efficiency with which the fly ash can be electrostatically precipitated comprising the steps of:

• passing sulfuric acid conditioning agent under pressure through a first line into a lance incorporating a sonic atomizing nozzle;
• heating a portion of said first line adjacent said lance so that said acid will be heated to a temperature higher than ambient but lower than its vaporizing temperature and which is sufficient to increase its temperature to at least about 93.degree. C. before it leaves the nozzle;
• and
• passing a gas under pressure through a second line into said nozzle, said gas pressure being at least about 10 psig higher than the liquid acid pressure, and said nozzle incorporating means to produce sonic vibrations capable of breaking up said liquid acid into a mist having a means droplet size no greater than about 10 microns.