Noxious-component removal from flue gas and compositions useful therefor

A gas-purification system which comprises:

• means to separate into two portions a raw gas stream containing noxious components,
• means to contact one portion intimately with dry sorption agent to remove noxious components therefrom,
• means to separate dry sorption agent from the portion in which it has been in contact,
• means to admix separated dry sorption agent with milk of lime,
• plural-stage fluid oxidation means,
• means to adjust the pH in successive stages of the plural-stage fluid oxidation means so that such pH in successive stages increases from about 4.5 to about 7.5,
• means to scrub the other of the two portions of the raw gas stream with wash liquid,
• means to conduct thus-used wash liquid to the plural-stage fluid oxidation means,
• means to separate effluent from solids in oxidized wash liquid,
• means to recirculate effluent to the scrubbing means and
• means to mix scrubbed gas with that which has been intimately contacted with dry sorption agent to form an admixture having a temperature in excess of the dew point of any corrosive constituents remaining therein.

A gas-purification system which comprises:

• fluidized bed pretreatment means to remove noxious components from a raw gas stream;
• means to separate a thus-treated stream into two portions,
• means to conduct one portion to dry purification means and means to conduct the remainder to wet purification means,
• the dry-purification means comprising means to add sorption agent to and intimately admix it with the one portion of pretreated gas, means to separate thus treated gas from sorption agent, means to conduct separated sorption agent to and into the fluidized bed means and means to convey separated gas to a mixing means,
• the wet-purification means comprising means to scrub the remainder of the gas with washing liquid, means to withdraw sorption agent from the fluidized bed means and incorporate it in the washing liquid and means to convey thus-washed gas to the mixing means, and
• means to recombine and to admix the two portions of thus treated gas in the mixing means to form one stream having a temperature in excess of the dew point of corrosive components remaining therein.