Method for operating a claus burner

1. A method for operating a burner used in a thermal step of a Claus process, wherein the burner includes at least one combustion air port, at least one oxygen port, and at least one fuel port, and

wherein an air flow is fed to the at least one combustion air port, an oxidant flow is fed to the at least one oxygen port, and a hydrogen sulphide containing feed gas flow is fed to the at least one fuel port, comprising:

feeding the oxidant flow which includes an oxygen flow of technical pure oxygen with an oxygen concentration of at least 90 vol. % to the at least one oxygen port and optionally feeding a second gas flow to the oxygen flow for providing a mixture of air and oxygen to the at least one oxygen port;

determining whether the oxygen flow is below a pre-set minimum flow at the at last one oxygen port; and

splitting the air flow if the oxygen flow is below the pre-set minimum flow into a main air flow fed to the at least one combustion air port, and a side air flow as the second gas flow to be combined with the oxygen flow for creating an oxygen-enriched side air flow fed to the at least one oxygen port.

2. The method of claim 1 , further comprising controlling the air flow based upon an acid gas flow in the hydrogen sulphide containing feed gas flow and on the oxygen flow.

3. The method of claim 1 , further comprising controlling the air flow based upon analysis of tail gas leaving the Claus process.

4. The method of claim 1 , wherein the hydrogen sulphide containing feed gas flow comprises:

a first gas stream including hydrogen sulphide but essentially no ammonia; and

a second gas stream including hydrogen sulphide and up to 50 percent by volume ammonia.

5. The method of claim 4 , wherein the second gas stream includes the hydrogen sulphide and at least 30 percent by volume ammonia.

6. The method of claim 1 , further comprising enriching the oxygen concentration for increasing a temperature of the burner in the Claus process for oxidation and destruction of ammonia.

7. A burner of a Claus plant, comprising:

at least one combustion air port, at least one oxygen port, and at least one fuel port;

a side supply line through which a side flow of air is provided upstream of the at last one oxygen port;

an oxygen supply line connecting a source of technical pure oxygen with the at least one oxygen port, the oxygen supply line including a flow control unit operatively associated with the side supply line, the flow control unit including a first branch through which a first oxygen flow passes and a second branch through which a second oxygen flow passes with a higher percent by volume amount of oxygen than the first oxygen flow, wherein each of the first and second branches are controlled for providing oxygen to the side air flow of the side supply line based upon whether an oxygen flow at the at least one oxygen port is below a pre-set minimum flow.

8. The burner of claim 7 , wherein the flow control unit is located upstream of a point where either of the first and second oxygen flows are fed into the side air flow.

9. The burner of 8 , wherein the first branch comprises a low-level enrichment control valve, and the second branch comprises a mid-level enrichment control valve.

10. The burner of claim 9 , wherein the low-level enrichment control valve and the mid-level enrichment control valve are arranged in parallel.

11. The burner of claim 7 , wherein the at least one oxygen port is located closer to the at last one fuel port than to the at least one combustion air port.

12. The burner of claim 7 , wherein the at least one oxygen port comprises an oxygen lance or alternatively a plurality of oxygen lances.