Abstract: A method and apparatus for measuring the acid gravity in an inorganic acid-organic fluid system permits constant monitoring of the acid gravity thus allowing the acid strength to be maintained at an optimum level. Particularly in a system such as an alkylation reactor, where product quality is dependent upon acid strength, the acid gravity measuring method and apparatus assures high product quality. A collecting vessel receives the inorganic acid-organic fluid mixture and the acid gravitates from the organic fluid in a disengaging chamber. The acid then enters an acid-analyzing section which includes acid gravity measuring means for determining the specific gravity of the separated acid. By continuously draining the fluid from the disengaging chamber and the acid-analyzing section, fresh fluid can be continuously introduced and the acid gravity continuously analyzed.

Abstract: Improvements in heat exchanging of distillation steps in sulfuric acid alkylation processes; removing water from the vaporous overhead fraction of a sulfuric acid alkylation process distillation step or deisobutanizer to enable mixing thereof with the vaporous hydrocarbon effluent from the reaction zone which contains sulfur dioxide vapors sulfur trioxide and H.sub.2 SO.sub.4 mist, thus permitting mixing of the vaporous fraction and effluent for compression before use as a compressed heat exchanging medium in the alkylation process; sulfuric acid alkylation with deisobutanizer tower overhead effluent acid wash.

Abstract: Improvements in alkylation effluent flash vaporization systems used in processes of alkylating isoparaffinic hydrocarbons with olefinic hydrocarbons in the presence of acid catalyst and an excess of isoparaffinic hydrocarbons; improvements in heat sources used in such alkylation effluent flash vaporization systems, specifically utilizing hot and compressed isoparaffinic hydrocarbon vapors generally available in such systems from such sources as fractionation (deisobutanizer) overhead or vapor flashing processes utilized in cooling the reaction step or both; improvements in alkylation effluent flash vaporization systems which reduce the load on the conventional step of retrieving excess isoparaffinic hydrocarbons from the alkylation reaction effluent for recycle to the reaction step.