Chemistry of inorganic compounds – Modifying or removing component of normally gaseous mixture – Sulfur or sulfur containing component
Patent
1995-10-19
1997-03-11
Straub, Gary P.
Chemistry of inorganic compounds
Modifying or removing component of normally gaseous mixture
Sulfur or sulfur containing component
42324312, 423539, 423522, 4235671, 4235741, 422161, 422168, 422170, 422172, B01D 5348, B01D 5374
Patent
active
056098413
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The invention relates to a method and apparatus for generating sulphuric acid, condensed sulphur dioxide or elementary sulphur from a flow gas containing oxidized sulphur compounds, such as originates for example from a coal-fired electricity power plant.
BACKGROUND ART
In the operation of a coal-fired electricity plant, there is produced an exhaust gas flow which is contaminated with compounds containing sulphur, in particular oxidized sulphur compounds. In other processes, for example in the manufacture of sinters needed for charging in the blast furnace process in the iron and steel industry, waste gas flows containing also sulphur occur. These waste gas flows represent a significant environmental hazard, in that their release into the atmosphere causes acidification of the environment. Consequently, production installations in which such gas flows occur are usually provided with apparatus for removing the compounds containing sulphur from the gas flow. However, such gas cleaning systems are relatively costly and often just shift the environmental problem from one place to another. One known example of this is the system in which compounds containing sulphur are removed from a waste gas bound to chalk thereby creating a large problem of disposal.
EP-A-217567 is mentioned as describing treatment of a gas containing a large proportion of SO.sub.2 to prepare it for the Claus reaction which generates elementary sulphur.
NL-A-7505940 describes concentration of sulphur dioxide from a waste gas containing sulphur dioxide by absorbing the sulphur dioxide and then regenerating a gas flow containing sulphur dioxide at higher concentration. The latter gas flow, before being fed to a Claus reactor, is mixed with a reducing gas which is generated from the waste gas from the Claus reactor.
DISCLOSURE OF THE INVENTION
The object of the invention is to provide a method and apparatus for removing the compounds containing sulphur from a gas flow while avoiding the foregoing environmental and disposal problems, and by which valuable products may be obtained such as sulphuric acid or elementary sulphur.
In accordance with the invention, there is provided a method of treating a flow of gas containing oxidized sulphur compounds to obtain one of sulphuric acid, condensed sulphur dioxide and elementary sulphur, comprising the steps of first component flow from a wet gas scrubber in the form of a flow of water containing at least 30% of the total oxidized sulphur compounds in said flow of gas and a second component gas flow leaving said wet gas scrubber containing at least a part of the remainder of the total oxidized sulphur compounds in said flow of gas; containing oxidized sulphur compounds in a concentration of at least 2.5% by volume; flow in water, and converting the oxidized sulphur compounds therein into hydrogen sulphide; and sulphide of step (iii) to a processing apparatus which manufactures from them one of sulphuric acid, condensed sulphur dioxide and elementary sulphur.
Typically, the second component gas flow contains, except for any leakage losses, all the remainder of the oxidized sulphur compounds left after formation of the first component flow, but in the invention a part of the initial flow of gas may be used later in the process as described below. Such a part is ignored in the calculation of percentage amounts in the component flow herein.
It has been found that from both the standpoint of energy consumption and the standpoint of chemical yield, by the method in accordance with the invention a system can be provided which is advantageous for cleaning waste gas flows containing sulphur and by which, moreover, economically valuable products may be obtained.
The invention is especially suitable for treating gas flows containing contamination with oxidized sulphur compounds at a level below 5% by volume, e.g. in the range 1000 to 9000 ppm.
In another aspect of the invention there is provided apparatus for treating a flow of gas containing oxidized sulphur compounds to obtain one of sulph
REFERENCES:
patent: 3962405 (1976-06-01), Annesser et al.
patent: 4070441 (1978-01-01), Pessel
patent: 4091075 (1978-05-01), Pessel
patent: 5304361 (1994-04-01), Parisi
den Hartog Adrianus J.
Greefkes Johannes
Hoogovens Staal B.V.
Straub Gary P.
Vanoy Timothy C.
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