Abstract: To effect a quasi-isothermal catalytic reaction of SO.sub.2 to SO.sub.3, a plurality of consecutive rows of banks of cooling tubes, are provided in the bed of shaped catalyst bodies in a contact reactor in such a manner that the banks of succeeding rows are staggered from the banks of the preceding rows. The distance between the cooling tubes in the banks is so selected that a penetration of entire catalyst bodies into the banks will virtually be prevented. The banks are so designed that the pressure drop of the gas in the banks is approximately the same as the pressure drop in the layer of catalyst between the bank. The distance between the banks is larger than the width of the banks.

Abstract: In flue gases or other humid exhaust gases which contain NO.sub.x and SO.sub.2, the NO.sub.x content is reduced and the SO.sub.2 content is oxidized to SO.sub.3 by a catalytic processing and the SO.sub.3 content is subsequently condensed as sulfuric acid. In order to prevent a clogging and deterioration of the catalyst and a contamination of the sulfuric acid the flue gas is subjected before the catalytic processing to a fine dedusting by a scrubbing with hot dilute sulfuric acid. In dependence on the water content of the flue gases the concentration of sulfuric acid in the dilute sulfuric acid and the temperature of the latter are adjusted so that no water will be transferred from the flue gases to the dilute sulfuric acid and no water or only a small amount of water will be transferred from the dilute sulfuric acid to the flue gas.

Abstract: In flue gases or other humid exhaust gases which are relatively cold and contain SO.sub.2, NO.sub.2 and other gaseous pollutants, the SO.sub.2 content is oxidized to SO.sub.3 and the NO content is reduced by a catalytic treatment, the SO.sub.3 content is condensed as sulfuric acid and other gaseous pollutants are removed by being scrubbed with aqueous liquids at low temperatures. In order to heat up the flue gas to the temperature required for the catalysis, the flue gas is heated up in a first heating-up stage by an indirect heat exchange with the catalytically treated gas before the catalytic treatment, the heated-up gas is heated up further in a second heating-up stage to the temperature required for the catalytic treatment, the catalytically treated gas which has been cooled in the first heating-up stage is cooled further in an indirect heat exchanger below the dew point temperature of sulfuric acid and is subsequently fed to an SO.sub.3 condenser.

Abstract: Flue gases or other contaminated humid exhaust gases which contain SO.sub.3 are cooled by an indirect heat exchange in a heat exchanger to a temperature below the dew point temperature of sulfuric acid and are cooled further to a predetermined temperature in an SO.sub.3 condenser by means of dilute sulfuric acid, which is sprayed to flow in a countercurrent to the gas, whereby dilute sulfuric acid having a predetermined concentration is condensed. The gas leaving the SO.sub.3 condenser is scrubbed and cooled to a temperature from 40.degree. to 55.degree. C. in a fine scrubber by a treatment with a sprayed aqueous liquor. The exit gas is reheated to a predetermined temperature in a reheater by a treatment with sprayed dilute sulfuric acid from the SO.sub.3 and after the condensation of SO.sub.3 is passed through a filter. Dilute sulfuric acid from the reheater is sprayed into the SO.sub.3 condenser.

Abstract: Cleaned flue gases normally accumulate as steam-saturated gases with temperatures of from 40.degree. to 55.degree. C. after wet cleaning processes for the removal of sulfur and/or nitrogen compounds. Before being let off through a stack, however, these gases have to be heated to at least 72.degree. C.This invention relates to a process for reheating flue gases after wet cleaning.

Abstract: SO.sub.2 -containing, hot gases are catalytically converted in part in a first contacting stage. The water and the SO.sub.3 formed is removed from the reaction gas. The remaining gas is heated and then supplied to the second contacting stage. The water vapor content in the reaction gas delivered by a first contacting stage corresponds to an H.sub.2 O/SO.sub.3 mole ratio below 1. The reaction gas delivered by the first contacting stage is precooled by an indirect heat exchange to such a temperature that the wall temperatures of the heat exchanger are above the dew point temperature of the reaction gas. The precooled reaction gas entering a condensing stage is contacted in a venturi with cocurrent sulfuric acid of 98.0 to 100% concentration and a temperature of at least 95.degree. C. The exit temperature of the gas from the condensing stage is maintained at least at 120.degree. C.

Abstract: A process for the production of sulfuric acid from wet sulfur dioxide containing gases is disclosed. The sulfur dioxide containing gas is initially purified and cooled, then predried with dilute sulfuric acid, finally dried with concentrated sulfuric acid, converted to sulfur trioxide catalytically and, the sulfur trioxide is absorbed in sulfuric acid. Preliminary drying removes more water than needed to maintain the water balance in the following process steps. A portion of the dilute acid from the preliminary drying is concentrated prior to recycle to the preliminary drying step and another portion of the acid from the preliminary dryer is added to the sulfur trioxide absorber to adjust the water balance in the acid circulating between the final dryer and the sulfur trioxide absorber.

Abstract: A process for the recovery of sulfuric acid from waste sulfuric acid containing iron sulfate and from solid iron sulfate of high water content of crystallization which consists essentially of:A. concentrating waste sulfuric acid to an acid concentration of 25-55 weight percent, based upon the suspension, by removing water therefrom;B. mixing the concentrated acid of Step A with recycled concentrated sulfuric acid obtained from Step E to form a resultant acid mixture of acid concentration of 30-65 weight percent, based upon the suspension;C. adding said solid iron sulfate of high water content of crystallization to the acid mixture of Step B thereby obtaining iron sulfate of low water content of crystallization;D. separating the iron sulfate of low water content from the resultant sulfuric acid solution of Step C;E. concentrating the separated sulfuric acid solution of Step D to an acid concentration of 45-70 weight percent, based on salt-free acid, and recycling at least a portion thereof to Step B; andF.

Abstract: Sulfuric acid is produced from sulfur trioxide-containing humid gases by a process wherein the sulfur trioxide-containing humid gases are directly cooled with aqueous sulfuric acid, sulfuric acid is condensed and the gas is cooled below dew point of the sulfuric acid, and the water not required to form sulfuric acid is discharged as water vapor with the end gases.

Abstract: In the removal of water from a gas by contact with sulfuric acid, the improvement which comprises supplying the sulfuric acid in finely divided form having a surface of about 10.sup.4 to 10.sup.7 m.sup.2 /h at a concentration of about 95 to 99% and a temperature of about 35.degree. to 80.degree. C and with a contact time of about 0.2 to 2 seconds, whereby the residual moisture content of the gas is reduced to about 30 to 250 mg of H.sub.2 O/Nm.sup.3. Preferably the sulfuric acid is sprayed through a constriction into a vessel through which the gas is passed. The large sulfuric acid surface area permits high levels of dehydration to be achieved with far less sulfuric acid than heretofore believed possible and with small vessels and minimal contact times. Contact may be effected serially in several stages with the spent acids combined, brought up to initial concentration and recirculated.

Abstract: Process for production of SO.sub.3 by catalytic oxidation of SO.sub.2 which comprises carrying out the oxidation in two stages with intermediate absorption. The conversion of SO.sub.2 in the first stage is about 70-80% for a starting gas which is a cooled and cleaned roaster gas and 70-90% for a starting gas which is a sulfur combustion gas. The second stage comprises two catalyst beds, and the gas is cooled intermediate the beds. High overall conversion is obtained with low catalyst requirement.

Abstract: Gases having a high SO.sub.2 content are catalytically reacted in a contacting zone having a plurality of series-connected contacting trays. A partial stream of partly reacted gases from the contacting zone containing SO.sub.3 is admixed with the SO.sub.2 containing gas before entering the first contacting tray. The gases are subjected to interstage cooling between contacting trays. At least a portion of the partly reacted gases is passed through an absorber prior to mixing with the feed stock gas having a high SO.sub.2 content. The rate at which SO.sub.3 is absorbed is increased in dependence on the loss of catalyst activity in the contacting zones such that the conversion of SO.sub.2 to SO.sub.3 in the contacting trays remains approximately constant.

Abstract: A catalytic reactor for converting sulfur dioxide to sulfur trioxide, suitable for high throughput rates of up to about 500,000 standard cubic meters per hour. The reactor includes a plurality of separate reaction chambers each containing catalyst trays connected in parallel in the gas flow path. The catalyst trays define gas spaces and alternate gas spaces are provided with inlets for supplying a partial stream of the sulfur dioxide containing gases which are divided in the gas spaces. The gas spaces adjacent to the gas spaces provided with inlets are provided with outlets for withdrawing partial streams of the gases which have passed through the catalyst trays.

Abstract: A process for removing sulfur trioxide from gases wherein the sulfur trioxide-containing gas is treated with sulfuric acid in a Venturi absorber, the sulfur-trioxide laden sulfuric acid is passed in indirect heat exchange with a cooling fluid within the widening outlet of the absorber and the sulfur trioxide-laden sulfuric acid is separated from the gas phase.

Abstract: Sulfur compounds oxidizable to form sulfuric acid and organic compounds oxidizable to CO.sub.2 and H.sub.2 O are removed from an exhaust gas of a contact-process plant for producing sulfuric acid by treating the exhaust gas with a scrubbing solution consisting of dilute sulfuric acid and peroxydisulfuric acid. The peroxydisulfuric acid is produced electrolytically from fresh dilute sulfuric acid and the resulting electrolyte is continuously introduced into the scrubbing acid cycle. The exhaust gas is treated in a vertical venturi with uniflow, i.e. codirectional flow of the gas and the scrubbing solution, and the gas is then passed through a horizontal venturi and subsequently upwardly through a packing layer.CROSS-REFERENCE TO RELATED APPLICATIONThe present Application is related to the commonly assigned copending application Ser. No. 308,849 filed Nov. 22, 1972 and entitled METHOD OF REMOVING GASEOUS IMPURITIES FROM WASTE GASES now abandoned.