Chemistry of inorganic compounds – Modifying or removing component of normally gaseous mixture – Sulfur or sulfur containing component
Patent
1984-04-20
1987-03-10
Heller, Gregory A.
Chemistry of inorganic compounds
Modifying or removing component of normally gaseous mixture
Sulfur or sulfur containing component
423512A, 423545, C01B 1700
Patent
active
046490337
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention refers to a process aimed at the elimination of air pollution caused by the burning of Sulphur containing fuels in all kinds of industry and equipment of all sizes. The process requires less investment than other alternative processes and produces a commercial end-product.
BACKGROUND ART
One of today's main concerns has been to eliminate air polluting agents resulting from the burning of Sulphur containing fuels, without generating inadequate by-products. Many of the processes presently used require large investments in equipments and installations, normally without return or with high added operational costs.
DISCLOSURE OF INVENTION
Aiming at solving or minimizing these problems, this process has been developped. Basicaly simple, easily retrofitted into the polluting equipments, with low investment costs, this process produces a high value end-product. Specifically, the aim of this invention is to transform all Sulphur Dioxide (SO.sub.2) and Sulphur Trioxide (SO.sub.3) existing in the combustion gases, to Ammonium Sulphate. This is obtained through the reaction of SO.sub.3 and SO.sub.2 with Ammonia, preferably in gaseous state, which is injected directly into the combustion gases. The collected stable end-product is Ammonium Sulphate [(NH.sub.4).sub.2 SO.sub.4 ] which is separated from the flue gases.
These and other objectives of this invention are obtained by this process which comprises the following steps: undertake at least one injection of Ammonia (NH.sub.3) in the combustion gases at temperatures between 250.degree. C. and 600.degree. C., in quantity sufficient to react with all the SO.sub.3 which is present and with part of the existing SO.sub.2 ; cool the gases to a temperature lower than about 65.degree. C.; separate the submicron and micron size particles from the combustion gases; collect the (NH.sub.4).sub.2 SO.sub.4 from the separating equipment, and send the desulphurized combustion gases to the flue.
Considering the possibility of providing more then one injection point of Ammonia (NH.sub.3), this process has foreseer the division of the injection into: a first injection of gaseous NH.sub.3 (Ammonia) into the 250.degree. C. to 600.degree. C. combustion gases and in a quantity sufficient to react with all the present SO.sub.3, and a second injection of gaseous NH.sub.3 at a region where the combustion gases are at a 65.degree. C. to 250.degree. C. temperature range and in a quantity sufficient to react with at least a part of the existing SO.sub.2.
In this case, the first injection is directed mainly the neutralization of the SO.sub.3.
In case of injection of all the Ammonia (NH.sub.3) in the 250.degree. C. to 600.degree. C. combustion gases temperature range, the NH.sub.3 will react with all present SO.sub.3 and the rest of NH.sub.3 will intermix with the combustion gases stream, up to the point where the temperature permits the occurence of an irreversible reaction between the SO.sub.2 and NH.sub.3.
As already established technically, the SO.sub.3 is a gas formed during the combustion of Sulphur containing fuels, by the reaction of gaseous SO.sub.2 with molecular Oxygen (O.sub.2), by the reaction of SO.sub.2 in the flame with atomic Oxygen and by catalytic oxidation of SO.sub.2 in the heat transfer surfaces under high temperatures. The corresponding reactions are the following:
Without the presence of catalysers, the burning of Sulphur containing fuels results in up to 5% SO.sub.3 in the total of SO.sub.x compounds. In spite of the fact that gaseous Ammonia reacts with SO.sub.3 in the temperature range of 250.degree. C. to about 600.degree. C., it has been verified that the ideal temperature range is 300.degree. C. to 400.degree. C. In this range, the reation of SO.sub.3 with NH.sub.3 is instantaneous resulting in (NH.sub.4).sub.2 SO.sub.4 (Ammonia Sulphate) and eliminating the possibility of corrosion in the surfaces which would have been contacted by the SO.sub.3. This corrosion occurs due to the formation of liquid Sulphuric Acid (H.sub.2 SO
REFERENCES:
patent: 3508868 (1970-04-01), Kiyoura
patent: 3523407 (1980-08-01), Humbert
patent: 3709977 (1973-01-01), Villiers-Fisher
patent: 3928536 (1975-12-01), Lewis
patent: 4064219 (1977-12-01), Yamashita
Chemical Abstracts, vol. 95, No. 12, Sep. 1981, 102276y.
De Oliveria Paulo R. M.
Krepel Pedro A.
Ladeira Newton C.
Marante Adilson P.
Heller Gregory A.
K,L+M Industria E Comercio S/P
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