The above mentioned invention describes a process for cooling a gas mixture of SO.sub.2 and/or SO.sub.3 and water, wherein the gas mixture is cooled by means of a first heat exchanger carrying a coolant. The temperature of the coolant lies above the dew point of the gas or gas mixture.

A process for the catalytic conversion of sulfur dioxide to sulfur trioxide to increase sulfuric acid regeneration from a spent sulfuric acid stream or other sulfur-containing stream includes replacing at least a portion of the atmospheric air typically used to oxidize sulfur dioxide to sulfur trioxide with oxygen by introducing oxygen-enriched air and/or pure oxygen feed streams into the process. A related apparatus for use in the process is also provided for catalytic conversion of sulfur dioxide to sulfur trioxide.

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.

Improved systems and methods are disclosed for producing sulfuric acid or for producing liquefied sulfur dioxide. The systems comprise a reactor for the combustion of sulfur to sulfur dioxide, a reactor gases heat exchanger, and either a contact apparatus and absorption apparatus combination or an absorption subsystem and liquefaction apparatus combination for producing either sulfuric acid or liquid sulfur dioxide respectively. By appropriately incorporating two recycle circuits, the first after the reactor gases heat exchanger and the second after the absorption apparatus or liquefaction apparatus, several advantages can be obtained. These include reductions in equipment size, complexity, power consumption energy losses, and suppression of NOx.

A process for the production of liquid acid, comprising the steps of: feeding liquid acid with a first concentration into a gas purification; passing a gas through the gas purification such that a second concentration of the liquid acid is reached; withdrawing the liquid acid from the sump of the gas purification, where in the gas purification sump is divided by a partition wall into a first and a second section. The concentration of the liquid acid collected in the first section is adjusted to the first concentration. The liquid acid with the first concentration from the first section is at least partially fed back into step and the liquid acid with the second concentration collected in the second section is at least partially withdrawn as product.

A process for the production of liquid acid, comprising the steps of: feeding liquid acid with a first concentration into a gas purification; passing a gas through the gas purification such that a second concentration of the liquid acid is reached; withdrawing the liquid acid from the sump of the gas purification, where in the gas purification sump is divided by a partition wall into a first and a second section. The concentration of the liquid acid collected in the first section is adjusted to the first concentration. The liquid acid with the first concentration from the first section is at least partially fed back into step and the liquid acid with the second concentration collected in the second section is at least partially withdrawn as product.

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 novel integrated system utilizing sulfur as alternative carbon-free fuel in an ammonia primary reformer combustion zone, with co-production of sulfuric acid from concentrated SO.sub.2 off-gas stream. Such integration shall reduce hydrocarbon fuel consumption, minimize CO.sub.2 emissions, and optimize overall energy utilization.

A method for manufacturing electronic-grade sulfuric acid includes following steps: providing sulfur-containing material; burning the sulfur-containing material with pure oxygen to obtain sulfur dioxide gas; converting the sulfur dioxide gas into sulfur trioxide gas; and processing the sulfur trioxide gas to obtain the electronic-grade sulfuric acid.

A process for production of elemental sulfur from a feedstock gas including from 15% to 100 vol % H2S and a stream of sulfuric acid, the process including: a) providing a Claus reaction furnace feed stream substoichiometric oxygen with respect to the Claus reaction, b) directing to a reaction furnace zone operating at elevated temperature such as above 900 C., c) directing to a sulfuric acid evaporation zone downstream said reaction furnace zone, d) cooling to provide a cooled Claus converter feed gas, e) directing to contact a material catalytically active in the Claus reaction, f) withdrawing a Claus tail gas and elemental sulfur, g) directing to a Claus tail gas treatment plant, with the associated benefit of a process involving injection of sulfuric acid in a sulfuric acid evaporation zone allowing high temperature combustion of said feedstock gas, including impurities, without cooling from evaporation and decomposition of sulfuric acid.