Debottleneck existing sulfur recovery units (SRU) or reduce size, capital and operating costs for new facilities by using oxygen, either to enrich or to replace combustion air.
Product: Bright yellow, high-purity sulfur. Claus tail gas is either processed in a tail gas clean-up unit (TGCU), or routed to the Claus incinerator where residual hydrogen sulfide (H2S) is oxidized to SO2.
In an air-based Claus plant, nitrogen from the combustion air usually comprises more than half of the molar flow through the plant. By replacing air with oxygen, plant capacity can be increased significantly. The level of air enrichment with oxygen and, hence, the level of uprating depend upon the feed-gas composition.
Process variations:
• Up to about 30% oxygen , only minor modifications to the plant would be expected.
• Above 30% oxygen concentration, a proprietary oxygen-compatible burner would be required using the SURE burner. Some limited modifications could be expected.
• For capacity increases in excess of about 100%, the SURE double combustion process could be used to achieve the desired expansion.
Operating conditions: The process uses a higher combustion temperature. The operating temperature is kept below 1,650°C—the normal refractory limit. Sulfur recovery efficiency for an oxygen-based Claus process is slightly better than that of air-based Claus and typically ranges between 95% and 98%, depending on process variables.
Economics: The cost of revamp is generally between 10% and 30%—only includes the cost for additional new plant capacity. The cost of a new oxygen-based Claus facility can save up to 35% of the installed cost for an air-based alternative.
Licensor: SIIRTEC NIGI (up to 30% O2), SURE Parsons/BOC through SIIRTEC NIGI
