Abstract: A process for the removal of hydrogen sulfide from a gas stream in which the gas stream is first passed through a Claus unit operating at a sub-stoichiometric ratio (H2S:SO2) of greater than 2:1 to produce a tail gas stream comprising less than 2000 vppm SO2. This tail gas stream is then treated to increase the sulfur recovery to at least 99.5% by first directly cooling the tail gas stream by contact with water as a coolant, followed by contacting the gas stream with a circulating stream of a dilute, absorbent solution of a severely sterically hindered secondary aminoether alcohol to further cool the gas stream, and then removing the H2S from the stream using a stronger absorbent solution of a severely sterically hindered secondary aminoether alcohol.

Abstract: A process for the removal of hydrogen sulfide from a gas stream in which the gas stream is first passed through a Claus unit operating at a sub-stoichiometric ratio (H2S:SO2) of greater than 2:1 to produce a tail gas stream comprising less than 2000 vppm SO2. This tail gas stream is then treated to increase the sulfur recovery to at least 99.5% by first directly cooling the tail gas stream by contact with water as a coolant, followed by contacting the gas stream with a circulating stream of a dilute, absorbent solution of a severely sterically hindered secondary aminoether alcohol to further cool the gas stream, and then removing the H2S from the stream using a stronger absorbent solution of a severely sterically hindered secondary aminoether alcohol.

Abstract: A method for removing sulfur-containing compounds is provided. In one embodiment, the method includes selectively separating a feed stream (118) comprising carbon dioxide and one or more sulfur-containing compounds, including hydrogen sulfide, at conditions sufficient to produce a first stream (122) comprising carbon dioxide and hydrogen sulfide and a second stream (124) comprising carbon dioxide and hydrogen sulfide. A molar ratio of carbon dioxide to hydrogen sulfide in the first stream is greater than a molar ratio of carbon dioxide to hydrogen sulfide in the second stream, and a molar ratio of hydrogen sulfide in the first stream to hydrogen sulfide in the second stream is about 0.005 or more.

Abstract: A method for removing sulfur-containing compounds is provided. In one embodiment, the method includes selectively separating a feed stream (118) comprising carbon dioxide and one or more sulfur-containing compounds, including hydrogen sulfide, at conditions sufficient to produce a first stream (122) comprising carbon dioxide and hydrogen sulfide and a second stream (124) comprising carbon dioxide and hydrogen sulfide. A molar ratio of carbon dioxide to hydrogen sulfide in the first stream is greater than a molar ratio of carbon dioxide to hydrogen sulfide in the second stream, and a molar ratio of hydrogen sulfide in the first stream to hydrogen sulfide in the second stream is about 0.005 or more.

Abstract: With sufficient oxygen but with no added fuel gas, recovering sulfur from a gas stream containing hydrogen sulfide by oxidizing the gas stream with heat exchange from heat generated in a thermal converter section of a sulfur recovery unit to convert the hydrogen sulfide in the gas stream to sulfur oxide, and thus form a sulfur oxide enriched gas stream. The sulfur oxide enriched gas stream is contacted with a solid adsorbent bed to extract the sulfur oxides and retain them as sulfur compounds, thus forming a sulfur oxide depleted gas stream. The adsorbent bed is then contacted with a reducing gas stream to reduce the retained sulfur compounds to hydrogen sulfide and/or sulfur dioxide and thereby form a hydrogen sulfide and/or sulfur dioxide bearing stream. Sulfur is recovered from the hydrogen sulfide and/or sulfur dioxide bearing stream, and the sulfur oxide depleted gas stream maybe sent to an incinerator or vented through a stack.

Abstract: Method and system for recovering sulfur from an ammonia acid gas stream containing hydrogen sulfide comprising the steps of combusting the ammonia acid gas stream with air or oxygen to convert the ammonia and the hydrogen sulfide therein to N.sub.2 and SO.sub.x, respectively, and thus form a nitrogen and sulfur oxide enriched gas stream. The nitrogen and sulfur oxide enriched gas stream is contacted with a solid absorbent bed to extract the sulfur oxides and retain them as sulfur compounds, thus forming a nitrogen bearing stream. The absorbent bed is then contacted with a hydrogen and/or hydrocarbon bearing stream to reduce the retained sulfur compounds to hydrogen sulfide and/or sulfur dioxide and thereby form a hydrogen sulfide and/or sulfur dioxide bearing stream. Sulfur is recovered from the hydrogen sulfide and/or sulfur dioxide bearing stream. The nitrogen bearing stream is sent to an incinerator or vented through a stack.

Abstract: A cyclic urea reaction product forms as a by-product of a hindered amine acid gas scrubbing process and results in an ultimate buildup of the material in the circulating amine scrubbing solution. The buildup of this material has a deleterious effect on acid gas removal rates and accordingly, results in inefficient acid gas removal. In the process of the present invention, the cyclic urea degradation product is removed from the circulating solution by employing a selective precipitation of the cyclic urea followed by filtration. The selective precipitation is carried out by cooling the circulating solution to a particular temperature level such that the cyclic urea comes out of solution while the other components remain in solution.

Abstract: Acidic gases such as carbon dioxide are removed from a normally gaseous mixture including the acidic component by contacting the gaseous mixture in an absorption zone with an acid absorbing scrubbing solution comprising a basic alkali metal compound and an activator for the compound, during which process at least a portion of the activator is converted to a cyclic urea. The solution is then transferred to the desorption zone to remove at least a portion of the absorbed acidic component. At least a portion of the partially desorbed scrubbing solution containing the cyclic urea is transferred from the desorption zone to a thermal conversion zone maintained at an elevated temperature wherein at least a portion of the cyclic urea is converted back to the activator.

Abstract: A cyclic urea reaction product forms as a by-product of a hindered amine acid gas scrubbing process and results in an ultimate buildup of the material in the circulating amine scrubbing solution. The buildup of this material has a deleterious effect on acid gas removal rates and accordingly, results in inefficient acid gas removal. In the process of the present invention, the cyclic urea degradation product is removed from the circulating solution by employing a selective precipitation of the cyclic urea followed by filtration. The selective precipitation is carried out by cooling the circulating solution to a particular temperature level such that the cyclic urea comes out of solution while the other components remain in solution.