In a method for cooling of process gas between catalytic layers or beds in a sulfuric acid plant, in which sulfuric acid is produced from feed gases containing sulfurous components like SO.sub.2, H.sub.2S, CS.sub.2 and COS or liquid feeds like molten sulfur or spent sulfuric acid, one or more boilers, especially water tube boilers, are used instead of conventional steam superheaters to cool the process gas between the catalytic beds in the SO.sub.2 converter of the plant. Thereby a less complicated and more cost efficient heat exchanger layout is obtained.

The present invention relates to a method for the catalytic removal of sulfur dioxide from waste gases in two reactors, wherein the first reactor is charged with an activated carbon catalyst. The method comprises: a. provision of a waste gas with a water content of less than 1 g H.sub.2O/Nm.sup.3 and an SO.sub.2 content of at least 5 ppm, b. introduction of the waste gases into a first reactor, c. catalytic conversion of the SO.sub.2 into gaseous SO.sub.3 in the first reactor by the activated carbon catalyst, wherein catalytic conversion on the activated carbon catalyst proceeds at a temperature of below 100° C., d. introduction of the prepurified waste gases from the first reactor into a second reactor, e. conversion of the SO.sub.3 with water into H.sub.2SO.sub.4 in the second reactor.

The invention relates to a method for manufacturing sulphuric acid, which involves converting sulphur dioxide SO.sub.2 into sulphur trioxide S0.sub.3, by injecting gaseous sulphur dioxide into a converter (1) inside which at least one mass (2) of a catalyst for the conversion is present, and according to which, during phases in which the injection of the gaseous sulphur dioxide is stopped, the space inside the converter (1) is heated in such a way as to maintain a minimum temperature of 200° C., and preferably 250° C., within each catalyst mass (2), characterized by the fact that the stopping of the injection of the sulphur dioxide is slaved to the starting of the heating, and vice versa.

In a converter for the catalytic oxidation of SO.sub.2 to SO.sub.3 in a sulfuric acid plant, which comprises a boiler section for the cooling of process gas between catalytic layers (beds), one or more water tube boilers (inter-bed boilers) having horizontal or slightly sloped tubes are used to cool the process gas between the catalytic layers (beds) in the converter. Each water tube boiler is provided with a process gas side bypass to control the temperature to the downstream catalyst layer.

A process plant including a Claus reaction furnace, a means of Claus gas cooling, a Claus conversion section, a means for Claus tail gas oxidation and a sulfuric acid section, wherein a sulfuric acid outlet of the sulfuric acid section is in fluid communication with an inlet of said Claus reaction furnace, as well as a related process. The process has the associated benefit of such a process avoiding undesired production of sulfuric acid, as well as reducing the Claus process gas volume.

A process for preparing sulfuric acid may involve oxidizing sulfur to sulfur dioxide by way of dried air in a first oxidation stage. The sulfur dioxide may then be oxidized to sulfur trioxide in a second oxidation stage. The sulfur trioxide may be absorbed by sulfuric acid in at least one absorption stage. Further, heated sulfuric acid may be drawn off from the absorption stage and used for generating steam. Process gas from an intermediate absorption stage may be recycled to the second oxidation stage and, in some cases, a final absorption stage after the process gas flows through the second oxidation stage.

A process plant including a Claus reaction furnace, a means of Claus gas cooling, a Claus conversion section, a means for Claus tail gas oxidation and a sulfuric acid section, wherein a sulfuric acid outlet of the sulfuric acid section is in fluid communication with an inlet of said Claus reaction furnace, as well as a related process. The process has the associated benefit of such a process avoiding undesired production of sulfuric acid, as well as reducing the Claus process gas volume.

The present invention, in general, relates to portable/transportable apparatuses, methods, and systems for generating and delivering sulfur trioxide on-site or near an item to be treated. The present invention also relates to portable/transportable apparatuses, methods, and systems for removing hydrocarbon contaminants including waxes, paraffins, resins, and ashpaltenes from surfaces and treating the surfaces to reduce hydrocarbon contaminant build-up on the surfaces.

A process for preparing sulfuric acid may involve oxidizing sulfur to sulfur dioxide by way of dried air in a first oxidation stage. The sulfur dioxide may then be oxidized to sulfur trioxide in a second oxidation stage. The sulfur trioxide may be absorbed by sulfuric acid in at least one absorption stage. Further, heated sulfuric acid may be drawn off from the absorption stage and used for generating steam. Process gas from an intermediate absorption stage may be recycled to the second oxidation stage and, in some cases, a final absorption stage after the process gas flows through the second oxidation stage.

In a converter for the catalytic oxidation of SO.sub.2 to SO.sub.3 in a sulfuric acid plant, which comprises a boiler section for the cooling of process gas between catalytic layers (beds), one or more water tube boilers (inter-bed boilers) having horizontal or slightly sloped tubes are used to cool the process gas between the catalytic layers (beds) in the converter. Each water tube boiler is provided with a process gas side bypass to control the temperature to the down-stream catalyst layer.