A flue gas stream arising from fossil fuel fired sources containing nitrogen oxide contaminants is conveyed through an exhaust duct into a quencher. In the quencher aqueous medium is sprayed into contact with the flue gas stream. The quenched flue gas stream is mixed with ozone distributed at a high velocity in a sub-stoichiometric amount for partial oxidation of NO.sub.xto form NO.sub.2 and prevent the formation of N.sub.2O.sub.5. The flue gas containing NO.sub.2 is absorbed into an acidic medium of a wet scrubber to form nitrous acid. In the scrubber the nitrous acid is mixed with selected compounds of ammonia to decompose the nitrous acid for release of nitrogen. With this process the consumption of ozone and the operating costs associated therewith eliminate the requirement to dispose of nitrate recovered from the scrubber purge stream.

A process for separating CO2 from a feed stream containing at least CO2 and at least one lighter component chosen among oxygen, nitrogen, argon, methane, CO and hydrogen and at least one component heavier than CO2, comprises cooling the feed stream in a heat exchanger (E1) to a temperature less than 30 C., separation of the cooled feed stream producing a first liquid enriched in CO2 and a first gas depleted in CO2, expanding at least part of the first liquid, producing a second liquid, vaporizing the second liquid in the heat exchanger (E1) producing a second gas, sending the compressed cooled second gas to the bottom of a scrubber column (K2) and removing a top gas of the scrubber column depleted in the at least one heavier component.

A scrubber for removing pollutant compounds from a gas stream. At least one gas channel introduces the gas stream to a lower portion of the scrubber. An inlet chamber directs the gas stream upwards to form a vertical gas stream. A constriction section has a vertical axis of symmetry and includes a centrally arranged venturi nozzle, and is above and in flow connection with an upper end of the inlet chamber for accelerating the vertical gas stream. A reaction chamber is arranged above and in flow connection with the constriction section. A reagent in the reaction chamber converts pollutant compounds in the gas stream to reaction products. A discharge channel in flow connection with the reaction chamber discharges gas and particles including the reaction products from the reaction chamber. A particle separator separates particles from the gas. A return channel recycles a portion of the particles to the reaction chamber.

A mixed raw material producing method for producing a mixed raw material includes preparing a glass raw material and an aqueous solution of sodium hydroxide; causing the aqueous solution to absorb carbon dioxide gas, to deposit sodium hydrogen carbonate in the aqueous solution; and mixing the sodium hydrogen carbonate with the glass raw material, to obtain a mixed raw material to be charged into a melting furnace.

A method for melting vitrifiable materials to produce flat glass, including: providing a furnace including: a melting tank, a fining tank, a neck, at least one inlet means located at the melting tank, an outlet means located downstream of the fining tank, and at least one extraction means of a flue gas located at the at least one upstream zone; charging the vitrifiable materials comprising raw materials and cullet in the melting tank with the at least one inlet means; melting the vitrifiable materials in the melting tank, fining the melt in the fining tank; flowing the melt from the fining tank to a working zone through the outlet means; and capturing CO.sub.2 from the flue gas.

A method for melting vitrifiable materials to produce flat glass, including: providing a furnace including: a melting tank, a fining tank, a neck, at least one inlet means located at the melting tank, an outlet means located downstream of the fining tank, and at least one extraction means of a flue gas located at the at least one upstream zone; charging the vitrifiable materials including raw materials and cullet in the melting tank with the at least one inlet means; cullet pre-heating; melting the vitrifiable materials in the melting tank; fining the melt in the fining tank; flowing the melt from the fining tank to a working zone through the outlet means; and capturing CO.sub.2 from the flue gas.