Waagner-biro Aktiengesellschaft

Ralf Lindbauer

Alfred Glasner

Franz Mair

In a sorption bed which is formed as a fluidized bed reactor possibly with circulating fluid, or as a fixed-bed reactor, for dry waste gas or waste air, purification sorbents introduced in the dry state are contacted at a temperature range between about 30 and 130.degree. C. by the waste gas with an at least 2% oxygen content and the acidic and/or oxidizable noxious gaseous components of the waste gas are found by the sorbent. Noxious gaseous components potentially include SO.sub.x, HCl, HF, NO.sub.x, Co and also hydrocarbons. The average dwelling time of the sorbents is at least about 20 minutes, in general several hours or days, and the average grain size of sorbent is at most 125 microns. The sorbent is introduced fresh and in stoichiometric ratio, with spent sorbent being correspondingly removed. Sorbents which may be considered are primarily baking soda (sodium bicarbonate), Ca(OH).sub.2 and Mg(OH).sub.2. Chlorides, fluorides, sulfate/sulfite mixtures, and nitrate/nitrite mixtures or mixtures of all of these compounds, occur in spent or used up sorbents. In particular, the reaction product that is carbonized in a low-temperature sorption stage, is reactivated through decarbonization by being returned to a combustion chamber of the combustion process, so that it can be used in a preliminary stage, primarily for removal of sulfur, chlorine, or fluorine. Due to the low temperature characteristics, the method herein can also be used for waste air purification, in particular for purifying tunnel waste air with carbon monoxide and hydrocarbons being oxidized. The spent or used-up sorbent is carbonized in the process, so that in this case, it can still be used completely (100%) for high temperature purification of the combustion chamber gases in a combustion chamber.

Method for waste gas treatment

Method of separating substances, notably SO.sub.2 and NO.sub.x where x is 1 or 2, from cooled flue gases, such as combustion exhaust gases containing low levels of impurities of the same. The gases are contacted with at least one substantially dry particulate absorbent including NaHCO.sub.3 which, at a release temperature below 400.degree. C., decomposes to form an activated absorbent including Na.sub.2 CO.sub.3 which serves to remove the harmful substances from the flowing gas.

Method for separation of impurities from flowing gas

In order to achieve the removal of SO.sub.2 and NO.sub.x together with the entrained dust from the combustion product gases discharged from the combustion chamber of a steam generator in which sulfur-containing fuel, such as for instance lignite or brown coal is being burned, NH.sub.3 and/or NaHCO.sub.3 or chemical substances which release these compounds or react with the combustion product gases to form these compounds are introduced into the already partially cooled combustion product gases in the temperature region below 500.degree. C. upstream of a dry separator, such as for instance a cloth filter. The entrained ashes are to contain CaO or Ca(OH).sub.2 and/or Na.sub.2 CO.sub.3, especially from a previous desulfurization unit, prior to the introduction of the NH.sub.3 thereinto.

Method of purifying combustion product gases contaminated with dust and

Method and apparatus for separating at least one harmful substance such as SO.sub.2, HCl or NO.sub.x where x is 1 or 2, from combustion exhaust gases containing the same. The exhaust gases are contacted with at least one particulate adsorbent which, at a release temperature below 400.degree. C., releases at least one of water, ammonia, or carbon dioxide, for reaction with the harmful substances. This reactant leaves the adsorbent in activated condition. Thus, the reactant and activated adsorbent serve to remove harmful substances from the flowing exhaust gas.

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Graz, Austria

Ralf Lindbauer