Method of and apparatus for processing sulfur-containing exhaust gas
AssigneeMetallgesellschaft Aktiengesellschaft
InventorDieter Wanner
Life of this patent
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Abstract
The sulfur-containing roasting gases of an ore-roasting plant are cooled in a waste-heat boiler, which produces steam, and then are subjected to particle removal in an electrostatic precipitator or cyclone. The gases are then scrubbed with recirculated aqueous sulfur acid and the gas is then passed through an electrostatic precipitator before being supplied to a plant for the contact process production of sulfur acid. According to the invention, the process is improved by condensing water from the gas in an indirect cooler between the scrubber and the final electrostatic precipitator while water or aqueous sulfur acid is sprayed into the gas upstream of the indirect gas cooler to augment the heat transfer from the gas to the cooled wall thereof.
Claims15
A method of treating a sulfur-containing exhaust gas produced in a metallurgical roasting furnace for use in a contact-process plant for the production of sulfuric acid which comprises the steps of:
- (a) abstracting heat from said exhaust gas by indirect heat exchange and thereafter removing particulates from the gas;
- (b) scrubbing the gas from step (a) with an aqueous sulfuric acid solution;
- (c) passing the scrubbed gas of step (b) into and through an indirect gas cooler to reduce the moisture of the gas to not more than about 60 g H.sub.2 O/m.sup.3 at 40.degree. C. (STP) and to reduce the temperature of the gas;
- (c.sub.1) spraying a sufficient amount of aqueous sulfuric acid into the gas while it is passing through the indirect gas cooler of step (c);
- (d) subjecting the indirectly cooled gas from step (c) to wet electrostatic precipitation;
- and
- (e) passing the gas subjected to the wet electrostatic precipitation of step (d) to a contact process plant for the production of sulfuric acid.
An apparatus for the treatment of a sulfuric-acid-containing gas produced in a roasting furnace for use in a contact-process production of sulfuric acid, said apparatus comprising:
- (a) a waste-heat boiler connected to said furnace for abstracting heat from said gas;
- (b) a dry-process electrostatic precipitator connected to said waste-heat boiler;
- (c) a scrubbing tower connected to said dry-process electrostatic precipitator and provided with a reservoir containing aqueous sulfuric acid and means for recirculating said aqueous sulfuric acid between said scrubbing tower and said reservoir;
- (d) an indirect cooler connected to said scrubbing tower for indirectly cooling the scrubbed gas therefrom, said indirect cooler comprising:
- (d.sub.1) an upright tower,
- (d.sub.2) vertically extending tubes in said tower and communicating with a gas space above said tubes,
- (d.sub.3) means for passing water into contact with external surfaces of said tubes, and
- (d.sub.4) means for spraying aqueous sulfuric acid into the space in (d.sub.2) for improving the heat exchange between the gas and said tubes in (d.sub.2) and for drying the gas;
- (e) a wet-process electrostatic precipitator downstream of said indirect cooler and in flow communication therewith;
- (f) means for collecting aqueous sulfuric acid from said indirect cooler and feeding the collected aqueous sulfuric acid to said reservoir;
- and
- (g) means for feeding aqueous sulfuric acid from said reservoir to said spraying means (d.sub.4).
Dependencies are inferred from the claim text.