Provided herein are methods and systems for treating a tail gas of a Claus process to remove sulfur-containing compounds. The method includes combusting a tail gas of a Claus process in an excess of oxygen gas to yield a thermal oxidizer effluent. The thermal oxidizer effluent includes sulfur dioxide, water vapor, and oxygen. The effluent is routed to a quench tower and contacted with a dilute aqueous acid quench stream to yield sulfurous acid, hydrated sulfur dioxide, or both. The sulfurous acid or hydrated sulfur dioxide is oxidized with the excess oxygen from the thermal oxidizer effluent to yield sulfuric acid.

Provided herein are methods and systems for treating a tail gas of a Claus process to remove sulfur-containing compounds. The method includes combusting a tail gas of a Claus process in an excess of oxygen gas to yield a thermal oxidizer effluent. The thermal oxidizer effluent includes sulfur dioxide, water vapor, and oxygen. The effluent is routed to a quench tower and contacted with a dilute aqueous acid quench stream to yield sulfurous acid, hydrated sulfur dioxide, or both. The sulfurous acid or hydrated sulfur dioxide is oxidized with the excess oxygen from the thermal oxidizer effluent to yield sulfuric acid.

A method for preparing an electronic grade sulfuric acid from a waste sulfuric acid solution includes the steps of: performing, in sequence, a concentration treatment, a cracking treatment, and a purification treatment; performing a first oxidation treatment on sulfur dioxide; performing a first absorption treatment and a second oxidization treatment; performing an evaporation treatment; performing a first removal treatment on an acid mist containing metal ions and anion impurities; performing a second absorption treatment; and performing a second removal treatment on residual sulfur dioxide.

A method for preparing an electronic grade sulfuric acid from a waste sulfuric acid solution includes the steps of: performing, in sequence, a concentration treatment, a cracking treatment, and a purification treatment; performing a first oxidation treatment on sulfur dioxide; performing a first absorption treatment and a second oxidization treatment; performing an evaporation treatment; performing a first removal treatment on an acid mist containing metal ions and anion impurities; performing a second absorption treatment; and performing a second removal treatment on residual sulfur dioxide.

A process plant and a process for production of sulfur from a feedstock gas including from 15% to 100 vol % H.sub.2S and a stream of sulfuric acid, the process including a) providing a Claus reaction furnace feed stream with a substoichiometric amount of oxygen, b) directing to a Claus reaction furnace operating at elevated temperature, c) cooling to provide a cooled Claus converter feed gas, d) directing to contact a material catalytically active in the Claus reaction, e) withdrawing a Claus tail gas and elementary sulfur, f) directing a stream comprising said Claus tail gas to a Claus tail gas treatment, wherein sulfuric acid directed to said Claus reaction furnace is in the form of droplets with 90% of the mass of the droplets having a diameter below 500 μm, with the associated benefit of such a process efficiently converting all liquid H.sub.2SO.sub.4 to gaseous H.sub.2SO.sub.4 and further to SO.sub.2.

A process plant and a process for production of sulfur from a feedstock gas including from 15% to 100 vol % H.sub.2S and a stream of sulfuric acid, the process including a) providing a Claus reaction furnace feed stream with a substoichiometric amount of oxygen, b) directing to a Claus reaction furnace operating at elevated temperature, c) cooling to provide a cooled Claus converter feed gas, d) directing to contact a material catalytically active in the Claus reaction, e) withdrawing a Claus tail gas and elementary sulfur, f) directing a stream comprising said Claus tail gas to a Claus tail gas treatment, wherein sulfuric acid directed to said Claus reaction furnace is in the form of droplets with 90% of the mass of the droplets having a diameter below 500 μm, with the associated benefit of such a process efficiently converting all liquid H.sub.2SO.sub.4 to gaseous H.sub.2SO.sub.4 and further to SO.sub.2.

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.

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.

Apparatus and methods for treating acid gas, which utilizes multi-stage absorption cycle of ammonia desulfurization to treat acid tail gas after pre-treatment of the acid gas, thereby achieving the purpose of efficient and low-cost treatment of acid tail gas. The parameters of the acid tail gas may be adjusted by a regulatory system such that the enthalpy value of the acid tail gas is in the range of 60-850 kJ/kg dry gas, for example, 80-680 kJ/kg dry gas or 100-450 kJ/kg dry gas, to meet the requirements of ammonia desulfurization, and achieve the synergy between the acid gas pre-treatment and ammonia desulfurization. Furthermore, hydrogen sulfide may be converted into sulfur/sulfuric acid plus ammonium sulfate at an adjustable ratio.

Apparatus and methods for treating acid gas, which utilizes multi-stage absorption cycle of ammonia desulfurization to treat acid tail gas after pre-treatment of the acid gas, thereby achieving the purpose of efficient and low-cost treatment of acid tail gas. The parameters of the acid tail gas may be adjusted by a regulatory system such that the enthalpy value of the acid tail gas is in the range of 60-850 kJ/kg dry gas, for example, 80-680 kJ/kg dry gas or 100-450 kJ/kg dry gas, to meet the requirements of ammonia desulfurization, and achieve the synergy between the acid gas pre-treatment and ammonia desulfurization. Furthermore, hydrogen sulfide may be converted into sulfur/sulfuric acid plus ammonium sulfate at an adjustable ratio.