Process and apparatus for removal of impurities from flue gases

A process for substantially removing at least one gaseous impurity selected from gases of heavy metals, salts, acids and hydrocarbons and submicron particle emissions contained in gases which comprises the steps of:

• cooling the gases by means of a liquified gas selected from nitrogen and air to a temperature in the range of 60.degree. C. to -20.degree. C. to precipitate said at least one impurity of said contained impurities;
• contacting the gases during cooling of the gases with a powdered sorbent selected from diatomaceous earth, perlite, expanded vermiculite, expanded sodium/calcium glass, expanded clay, and zeolites which has a surface area between 30 m.sup.2 /g to 600 m.sup.2 /g and a pore volume between 0.3 and 1.0 cc/g to collect said impurity;
• adding an alkali metal to said sorbent to adjust the pH of the sorbent to about 9 to 11;
• forming a filter bed of said sorbent in a filter chamber and passing the cooled gases through said filter bed;
• collecting said impurity by adsorbing and absorbing precipitated heavy metal and salts, condensed acids and hydrocarbons, and submicron emissions of the filter bed;
• recycling said sorbent until the pore volume of the sorbent is substantially saturated with said at least one impurity;
• and
• discharging the saturated sorbent.