Process for stripping nitrogen oxides and sulphur oxides, as well as optionally other noxious elements from flue gas from combustion plants, preferably boilers of electric plants supplied with fossil fuels, the nitrogen oxides being reduced into elemental nitrogen and the sulphur oxides as well as other noxious elements being stripped by a washing process. In order to improve this process of the above-mentioned type as to the simplicity of its implementation and the possible results, the present invention proposes a series of measures such as the addition of a monobasic and/or multibasic carbonic acid to EDTA with limestone or the like, the addition of phosphonic acid or the salt thereof to the washing liquid up to an electrochemical process whereby are added to the washing liquid of a conventional desulphuration plant salts which form with the nitrogen monoxide complexes which are reduced into elementary nitrogen and water by mixing them with formic acid to prevent the precipitation of iron-III-hollow hydroxide at a potentiostatic cathode.

Process for stripping nitrogen oxides and sulphur oxides as well as optionally other noxious elements of flue gas from combustion plants

The present invention relates to a cyclic continuous process and compositon for the removal of NO and SO 2 from a variety of fluid streams. A fluid stream containing NO and SO 2 is contacted with an aqueous solutin of water-soluble organic polymeric chelate containing a polyvalent metal, e.g., Fe (II). The NO is catalytically absorbed and in the presence of SO 2 , the imidodisulfonate is formed. Optionally, a reducing agent, such as sodium hydrogen sulfide, is added to maintain the polyvalent metal in the reduced state. The process next includes removal of the imidodisulfonate formed. The separation of water and low molecular weight materials and products, e.g. molecular weight below 500, usually occurs by ultrafiltration or dialysis, with recycle and re-use of the polyvalent metal chelate.

Process for the removal of NO from fluid streams using a water-soluble polymeric chelate of a polyvalent metal

An apparatus for treating a flue gas provided with a heater and an apparatus for removing NOx on the downstream side of an apparatus for removing SOx, where a heat exchanger for heat exchanging a treated gas from the apparatus for removing NOx with conbustion air is provided on the downstream side of the apparatus for removing NOx, whereby the waste heat of the treated gas can be efficiently utilized and the heat required for heating the flue gas can be reduced

Apparatus for treating flue gas

Oxides of nitrogen can be removed efficiently from a gas containing such oxides of nitrogen by bringing said gas into contact with an aqueous solution containing an organic acid alkali salt and a salt of metal selected from the group consisting of Fe, Co, Ni, Cu and Mn in the presence of a sulfurous acid alkali salt. The efficiency for removing oxides of nitrogen is much improved by use of a polybasic acid alkali such as ethylenediamine tetracarboxylic acid alkali salt or nitrilo-tricarboxylic acid alkali salt as said organic acid alkali salt.

An absorbing solution for the removal of nitrogen oxide form a gas containing same

Method for decreasing emissions of nitrogen oxides and sulfur oxides when burning fuel which contains nitrogen and sulfur. According to the invention this is carried out by feeding fuel (4) and oxygen-containing gas (5) into a combustion reactor (1) the temperature of which is preferably 900-1500oC, and that the combustion gases formed are directed into a suspension reactor (2) the temperature of which is preferably 750-1050oC and into which a pulverous material which binds sulfur oxides is fed so that the suspension density is 1-200 kg/m3, the oxygen concentration in the combustion reactor (1) and the suspension reactor (2) being controlled so that their total air coefficient is about 0.65-2, whereafter the gases are directed into an after-treatment reactor (3), into which oxygen-containing gas (12) is fed in order to adjust the oxygen concentration in the flue gases so that the residual oxygen concentration in the flue gases (13) emerging from the after-treatment reactor is 0.5-16, preferably 1-6% by volume.

Method for decreasing emissions of nitrogen oxides and sulfur oxides when burning fuels which contain nitrogen and sulfur

A method of removing a nitrogen oxide from an exhaust containing the same which comprises preparing an absorbent solution by adding divalent copper ions alone or a mixture of the divalent copper ions and divalent manganese ions to an acid aqueous solution containing sulfites or acid sulfites of ammonium, alkaline metals, or alkaline earth metals or a mixture of two or more of these compounds; and introducing the plant exhaust into the absorbent solution to carry out reaction between the sulfite radical of the absorbent solution and the nitrogen oxides contained in the exhaust to reduce the nitrogen oxides to nitrogen gas

Method of removing nitrogen oxides from plant exhaust

Powder and/or fine particles containing mainly oxides of iron or ferroalloys, which are used or generated in ironworks, steelworks, etc. are sieved to a grain size range between about 32 mesh and about 10mm and used as reduction catalyzer. A reactor is filled with said reduction catalyzer. Exhaust gas containing nitrogen oxides and with added ammonia is passed in contact with said reduction catalyzer through said reactor, while heating said reduction catalyzer to a temperature between about 300° C and about 370° C, whereby nitrogen oxides are removed from said exhaust gas by reduction. Said reduction catalyzer can be used as material for ironmaking, without requiring any further treatment, after use as catalyzer.

Method of removing nitrogen oxides from exhaust gas by reduction

A method for reducing NOx gas contained in an exhaust gas to harmless N2 gas with NH3 gas using an iron oxide catalyst, characterized in that said iron oxide catalyst comprises a substance consisting essentially of hematite crystals ( alpha -Fe2O3), and the peak intensity of X-rays diffracted on the (110) plane of the lattice of said crystal has a ratio of 0.6 to about 1.0 to that of X-rays diffracted on the (104) plane of said crystal lattice.

Method of reducing NO{HD x {b present in an exhaust to harmless N{HD 2

A method of removing nitrogen oxides from an exhaust which comprises the steps of contacting an exhaust containing nitrogen oxides and ammonia with a reducing catalyst received in a reactor to reduce the nitrogen oxides to nitrogen gas, wherein iron ore catalyst lumps having a particle size of 25 mm or less and forming a catalyst bed in the reactor are used as a reducing catalyst; the iron ore lumps of the catalyst bed are let to fall gravitationally through the reactor continuously or intermittently; and the iron ore catalyst lumps discharged from the reactor are either used as raw material for iron manufacture or fed back to the reactor to be reused as a reducing catalyst after being sieved

Method of removing nitrogen oxides from an exhaust

PURPOSE:A process wherein iron ores are used as a moving bed catalyst in catalytic reduction of nitrogen oxides in exhaust gas using ammonia.

Hiroshi Abe

Papers

Method of removing nitrogen oxides from plant exhaust

Method of removing nitrogen oxides from exhaust gas by reduction

Method of reducing NO{HD x {b present in an exhaust to harmless N{HD 2

Method of removing nitrogen oxides from an exhaust

Process for removal of nitrogen oxides in exhaust gas