Commercial production of sulfuric acid is almost entirely accomplished nowadays using the contact process. And the trend is to increase conversion efficiency and reduce emissions of unconverted sulfur dioxide. By using a special combination of contact catalyst beds, a single contact single absorption (SCSA) system can be engineered to achieve the conversion and emission capabilities of conventional double contact double absorption systems. Thus, the complexity and cost of incorporating a second absorption tower and associated heat exchanger in the system can be omitted. In the SCSA system, the initial catalyst bed or beds comprise vanadium oxide catalyst and the last catalyst bed or beds comprise platinum catalyst operating at a much lower temperature than the initial beds.

A contact process, sulfuric acid system and method are disclosed for producing sulphuric acid with improved operating efficiency in humid environments. The system comprises a pre-drying absorber for pre-drying humid air with weak sulfuric acid. Weak sulfuric acid from the pre-drying absorber is provided to a subsystem comprising two sulfur trioxide absorbers and a heat exchanger for the recovery of heat via steam production. This arrangement allows for a marked increase in steam production (i.e. energy efficiency). In a separate improvement, the emission apparatus for the system can be simplified using a peroxide tail gas scrubber comprising upper and lower scrubber sections in which the upper scrubber section consists essentially of tray type scrubbers.

The invention relates to a continuous process for purifying a gas containing 60-99 percent SO.sub.2 (sulfur dioxide) by volume and 1 to 40 percent steam by volume, followed by synthesis of SO.sub.3 (sulfur trioxide) without first drying the gas, and to an apparatus for carrying out said method.

A contact process, sulfuric acid system and method are disclosed for producing sulphuric acid with improved operating efficiency in humid environments. The system comprises a pre-drying absorber for pre-drying humid air with weak sulfuric acid. Weak sulfuric acid from the pre-drying absorber is provided to a subsystem comprising two sulfur trioxide absorbers and a heat exchanger for the recovery of heat via steam production. This arrangement allows for a marked increase in steam production (i.e. energy efficiency). In a separate improvement, the emission apparatus for the system can be simplified using a peroxide tail gas scrubber comprising upper and lower scrubber sections in which the upper scrubber section consists essentially of tray type scrubbers.

A method and system for cooling sulfuric acid aqueous solutions (H.sub.2SO.sub.4) belonging to the field of chemical processes, which is part of a contact process for production of sulfuric acid with or without energy recovery. The method comprises absorption of SO.sub.3, which produces heated concentrated sulfuric acid and indirectly cooling the hot acid. The method uses a sulfuric acid-inert coolant. A cooling step comprises an intermediate indirect acid-fluid cooling and a second fluid-water or fluid indirect cooling stepthird fluid, wherein when the process is of the type with energy recovery. A third step includes energy recovery, steam generation. A system to perform the method, which works next to the SO.sub.3 absorption tower comprises an acid cooling loop consisting of an intermediate acid-fluid heat exchanger; a second fluid-water heat exchanger, and when the process is of the type with energy recovery, said equipment further includes a steam generation boiler.

A method and system for cooling sulfuric acid aqueous solutions (H.sub.2SO.sub.4) belonging to the field of chemical processes, which is part of a contact process for production of sulfuric acid with or without energy recovery. The method comprises absorption of SO.sub.3, which produces heated concentrated sulfuric acid and indirectly cooling the hot acid. The method uses a sulfuric acid-inert coolant. A cooling step comprises an intermediate indirect acid-fluid cooling and a second fluid-water or fluid indirect cooling stepthird fluid, wherein when the process is of the type with energy recovery. A third step includes energy recovery, steam generation. A system to perform the method, which works next to the SO.sub.3 absorption tower comprises an acid cooling loop consisting of an intermediate acid-fluid heat exchanger; a second fluid-water heat exchanger, and when the process is of the type with energy recovery, said equipment further includes a steam generation boiler.

Sulfur trioxide is produced from a feed stream comprising sulfur-containing compounds and dissolved metals, such as alkali metals, in a plant comprising an incineration furnace, a waste heat boiler, a dilution air heater, a dust removal absorber and an SO.sub.2 converter. The plant may further comprise a sulfuric acid condenser for the production of sulfuric acid.

Sulfur trioxide is produced from a feed stream comprising sulfur-containing compounds and dissolved metals, such as alkali metals, in a plant comprising an incineration furnace, a waste heat boiler, a dilution air heater, a dust removal absorber and an SO.sub.2 converter. The plant may further comprise a sulfuric acid condenser for the production of sulfuric acid.

A catalytic reactor may have at least one reactor module and a shell that extends about a reactor center axis. The reactor module may include a gas distribution chamber, a gas collection chamber, and a catalyst. The gas distribution chamber may be connected to a shell-side gas feed. The gas collection chamber may be connected to a shell-side gas discharge. A catalyst bed between the distribution and collection chambers may extend transversely to the reactor center axis. The gas distribution and collection chambers are bounded by the catalyst bed and reactor walls. The gas feed either opens into the gas distribution chamber on the shell side or is connected to a pipe length that extends towards the reactor center axis and opens into the gas distribution chamber in the region of the reactor center axis. A height parallel to the reactor center axis of the gas distribution chamber reduces towards the reactor center axis starting from a mouth of the gas feed in the case of a shell-side connection.

A catalytic reactor may have at least one reactor module and a shell that extends about a reactor center axis. The reactor module may include a gas distribution chamber, a gas collection chamber, and a catalyst. The gas distribution chamber may be connected to a shell-side gas feed. The gas collection chamber may be connected to a shell-side gas discharge. A catalyst bed between the distribution and collection chambers may extend transversely to the reactor center axis. The gas distribution and collection chambers are bounded by the catalyst bed and reactor walls. The gas feed either opens into the gas distribution chamber on the shell side or is connected to a pipe length that extends towards the reactor center axis and opens into the gas distribution chamber in the region of the reactor center axis. A height parallel to the reactor center axis of the gas distribution chamber reduces towards the reactor center axis starting from a mouth of the gas feed in the case of a shell-side connection.