Sulfur recovery unit oxidation air management during SuperClaus to Claus switching

A control process for oxidation air management in a sulfur recovery unit, comprising:

• analyzing at least one parameter in the sulfur recovery unit, the sulfur recovery unit comprising:
• a gas feedstock inlet configured for receiving a gas feedstock comprising Hydrogen Sulfide (H2S);
• an oxidation air inlet configured for receiving an oxidation air feedstock;
• and
• a plurality of heaters;
• based on the at least one parameter, determining a switch from a SuperClaus section of the sulfur recovery unit to a Claus section of the sulfur recovery unit,
• wherein the Claus section comprises:
• a first oxidation air valve connected with the oxidation air inlet, the gas feedstock inlet and the oxidation air inlet being fed to a first combustion reactor configured for combustion of the gas feedstock in a presence of the oxidation air feedstock, producing a first process gas stream;
• a first sulfur condenser configured to condense the first process gas stream, producing a first sulfur stream and a first non-condensed process gas stream;
• a first Claus converter configured to convert the H2S in the first non-condensed process gas stream to elemental sulfur, producing a second process gas stream;
• a second sulfur condenser configured to condense the second process gas stream, producing a second sulfur stream and a second non-condensed process gas stream;
• a second Claus converter configured convert the H2S in the second non-condensed process gas stream to elemental sulfur, producing a third process gas stream;
• and
• a third sulfur condenser configured to condense the third process gas stream, producing a third sulfur stream and a third non-condensed process gas stream, and
• wherein the SuperClaus section comprises a catalyzing SuperClaus converter, a SuperClaus sulfur condenser, and at least one SuperClaus oxidation air flow control valve connected to the oxidation air inlet;
• continuously monitoring at least one condition in the sulfur recovery unit;
• and
• when the at least one condition reaches a predetermined threshold or range, opening the at least one SuperClaus oxidation air flow control valve to the SuperClaus section.