Toxic metal vapor phase compounds, and in particular, mercury and cadmium, are removed from waste incinerator combustion gases by contact with dry alkaline material and dry activated carbon followed by solids separation. The resulting gas is subjected to quench/wet scrubbing with recycle hydrochloric acid solution formed in situ by absorption of HCl from the gas. Blowdown liquid withdrawn from the recycle acid liquor, may be recycled to the incinerator or further treated by neutralization, precipitation, and filtration of the precipitated toxic metals.

Removal of mercury and cadmium and their compounds from incinerator flue gases

The present invention relates to a method for the removal of mercury from a gas stream. The method is characterized in that at a temperature above 170° C. the gas stream is contacted with a sorbent that as the active component is comprised of a mixture of substantially silica-alumina compounds and/or calcium compounds. According to a preference, the sorbent is kaolin, that may or may not be in the dehydrated form of meta-kaolin and is optionally obtained by thermal conversion of a material chosen from paper waste or residue from the paper industry. By this method it is possible to remove mercury at temperatures higher than room temperature. The invention also relates to a method for the removal of mercury from a gas stream, wherein the gas stream is contacted with a sorbent at a temperature above 50° C., which sorbent comprises as active substance a mixture of substantially silica-alumina compounds and/or calcium compounds, as well as with an oxidator. The invention also relates to a mercury-comprising sorbent obtained by this method and products manufactured therewith.

A method for the removal of mercury from a gas stream

An additive is sprayed into the combustion chambers of heating and waste incineration plants to prevent high temperature corrosion and to reduce the fly ash proportion in the exhaust gas. Also disclosed is a process for preventing high temperature corrosion and for reducing the fly ash proportion in the exhaust gas from heating and waste incineration plants. The disclosed additive consists of acid activated bentonite and/or oxide melts, in particular glass powder or glass dust with a melting point below 1000 ~C, and is sprayed into the gas chamber in areas in which the gas temperature exceeds 700 ~C.

Additive to be sprayed into the combustion chambers of heating plants and process for preventing high temperature corrosion

Flue gases are conveyed through a waste gas heat exchanger (5) and a flue gas desulphurising scrubber (1). Upstream of the waste gas heat exchanger (5) a mixture of particles comprising activated coal particles and particles of slaked lime and/or limestone is injected into the flue gases. The slaked lime or limestone reacts with the acidic constituents of the flue gases before entering the flue gas desulphurising scrubber (1) and prevents these constituents from acting on the activated coal particles during the wet cleaning process. These unused particles are therefore available for adsorption of the heavy metals and the organic pollutants, resulting in a corresponding saving of adsorption means. The activated coal particles can be re-circulated, and a portion of the re-circulated particles is conveyed through thermal desorption means (11) in each case.

Method and device for cleaning flue gases from furnaces

Removal of heavy metals from incinerator flue gases

Fine pulverulent calcium hydroxides are prepared which are particularly suitable for purifying gases and exhaust gases. For this purpose, surface-active substances in finely divided form are added to the burnt lime prior to slaking the burnt lime, during the slaking process to the water required for slaking and/or after slaking to the calcium hydroxide. Activated charcoal, activated aluminium oxide, silica gel and/or brown coal-hearth oven coke are used. The purification of the gases is carried out in the pneumatic flow process at temperatures above the dew point.

Process for cleaning gases and exhaust gases

The invention relates to a method for purifying gases and waste gases of acidifying gases, such as hydrogen chloride, hydrogen fluoride, sulfur dioxide and hydrogen cyanide, nitrogen oxides, hydrocarbons, chlorinated hydrocarbons, organic compounds and volatile heavy metals such as mercury, arsenic, antimony, cadmium and thallium. The gas or waste gas stream calcium hydroxide is admixed to the process was the added after deleting quicklime activated carbon, Braunkohlenherdofenkoks, activated alumina and / or silica gel. The purification is carried out in a temperature range from 20 to 1200 degrees, and the deposition of the solids takes place at Staubabscheidevorrichtungen.

Process for purification of gases and exhaust gases

Calcium hydroxides are produced which are particularly suited for the purification of gases and exhaust gases For this purpose, substances are added to the slaking water for dead-burnt line which enhance the reactivity of Ca(OH)2 These substances are alkalis such as NaOH or hydrate-forming substances such as CaCl2 or hydroxide-forming substances such as FeCl3 In addition, Hg-binding compounds such as NaHS or trimercapto-s-triazine can be deposited on Ca(OH)2 A further group of substances includes the heavy metals present in several oxidation stages, such as chromium, manganese, vanadium and similar, which act as catalysts Surfactants such as activated carbon and silica gel can also be combined with Ca(OH)2, thereby precipitating Hg and noxious acidic residues, for example HCl and SO2

Hermann Dr. Suchenwirth

Papers

Process for cleaning gases and exhaust gases

Process for purification of gases and exhaust gases

The use of reactive calcium hydroxide for purifying gases and exhaust gases