Configurations and methods for effluent gas treatment

A plant for catalytic reduction of sulfur dioxide in an oxygen-containing effluent gas, comprising:

• an effluent gas source that is configured to provide an effluent gas comprising oxygen and sulfur dioxide, wherein the effluent gas source is coupled to a first catalytic reactor to thereby feed the effluent gas into the first catalytic reactor;
• wherein the first catalytic reactor is further configured to receive a first portion of a recycle gas comprising hydrogen sulfide, the first reactor further comprising a catalyst that catalyzes a reaction in which the oxygen reacts with the hydrogen sulfide to form a sulfur dioxide-containing oxygen-free gas comprising water and sulfur dioxide;
• and
• a second catalytic reactor fluidly coupled to the first reactor and receiving the sulfur dioxide-containing oxygen-free gas, the second catalytic reactor further comprising a hydrogenation catalyst that catalyzes a reaction in which the sulfur dioxide from the oxygen-free gas and at least one of hydrogen and carbon monoxide react to form a reduced oxygen-free gas comprising hydrogen sulfide;
• wherein the second catalytic reactor is further configured to receive a second portion of the recycle gas in an amount effective to control effluent temperature of the second reactor;
• and
• wherein the recycle gas is a mixture of the reduced oxygen-free gas comprising hydrogen sulfide and a hydrogen sulfide-depleted absorber overhead product, and wherein a regulator is configured to adjust a ratio of the reduced oxygen-free gas comprising hydrogen sulfide and the hydrogen sulfide-depleted absorber overhead product.

A plant for desulfurization of a waste gas that dudes oxygen and sulfur dioxide, comprising:

• a first reactor that is configured to receive the waste gas from a waste gas source and further configured to receive hydrogen sulfide from a first portion of a recycle stream in an amount effective to catalytically deplete the waste gas from oxygen and to produce a sulfur dioxide-containing oxygen-depleted waste gas;
• and
• a second reactor that receives the sulfur dioxide-containing oxygen-depleted waste gas, wherein the second reactor is configured to allow addition of at least one of hydrogen and carbon monoxide from an external source to the oxygen-depleted waste gas in an amount sufficient to catalytically reduce the sulfur dioxide to hydrogen sulfide;
• wherein the second reactor is further configured to receive a second portion of the recycle stream in an amount effective to control effluent temperature of the second reactor;
• a recycling circuit that is configured to allow use of at least a portion of the hydrogen sulfide from the second reactor as the recycle stream;
• wherein the recycle stream is a mixture of the sulfur dioxide-containing oxygen-depleted waste gas and a hydrogen sulfide-depleted absorber overhead product;
• and
• wherein a regulator is coupled to the recycling circuit and configured to adjust a ratio of the sulfur dioxide-containing oxygen-depleted waste gas and the hydrogen sulfide-depleted absorber overhead product.