Process of separating hydrogen fluoride from gases

Claim 1

A process for removing hydrogen fluoride from a gas which comprises the combination of the following steps: a. introducing the gas into a fluidized bed reactor at a velocity of 1 to 5m/sec calculated for the empty reactor to form a gas-solid suspension in which the solids concentration decreases from bottom to top and wherein the solids have a particle size of 20 to 300 microns; b. extracting solids from said reactor substantially exclusively in an upward direction by entrainment with gas in a gas-solid suspension having a solids content of the order of 175 to 250 grams per cubic meter (STP) of the extracted suspension; c. separating the solids extracted in step (b) from the entraining gas without prior removal of the solids from the gas-solid suspension which has a dust resistivity adjusted to be below 10 12 Ohm-cm by means of an electrostatic precipitator directly following the reactor and constituting the sole gas/solid separator downstream of the reactor; d. simultaneously with the separation of the solids from the entraining gas classifying the separated particles of the solids in said electrostatic precipitator into fine-grain and coarse-grain fractions; e. recycling the coarse-grain fraction into the fluidized bed reactor to form a circulating fluidized bed therein while discharging the fine-grain fraction upon which impurities in said gas preferentially adsorb; and f. discharging gas from said electrostatic precipitator after the separation of said particles therefrom as an exhaust gas containing at most about 1 mg/m 3 (STP) of fluorine as HF.