Design case (air-only mode)
Design case (oxygen-enriched mode)
Parameters
Value
Parameters
Value
Sulphur content in feed, MTPD
600 (Two trains combined)
Sulphur content in feed, MTPD
600 (One train operating)
Process gas at reaction furnace outlet, MMSCFD 32.8 Reaction furnace temperature, ºC 1,160 Req. volume – reaction furnace, ft3 1,451 Req. volume – converter 1 catalyst, ft3 1,397 Req. volume – converter 2 catalyst, ft3 1,447 Duty – sulphur condenser 1, MMBtu/hr 12 Duty – sulphur condenser 2, MMBtu/hr 6.4 Duty – sulphur condenser 3, MMBtu/hr 4.6 Overall recovery, % 99.96 Emissions, SO₂ in stack (dry and O₂ free), ppmv 118.5
Process gas at reaction furnace outlet, MMSCFD 34.7 Reaction furnace temperature, ºC 1,389 Volume – reaction furnace, ft3 1,781 Volume – converter 1 catalyst, ft3 1,317 Volume – converter 2 catalyst, ft3 1,345 Duty – sulphur condenser 1, MMBtu/hr 16.5 Duty – sulphur condenser 2, MMBtu/hr 9.8 Duty – sulphur condenser 3, MMBtu/hr 6.1 Overall recovery, % 99.97 Emissions, SO₂ in stack (dry and O₂ free), ppmv 200
Table 2
Table 1
Design case (air-only mode) Both trains run at 50% each with atmospheric air producing 300 MTPD of sulphur. The AGE unit removes most CO₂, giv - ing a hotter feed. Table 1 shows all required key parameters. Design case (oxygen-enriched mode) When one train must be shut, the other takes the full 600 MTPD. Operators switch to oxygen at about 95% purity. The AGE unit continues to enrich fully. The active train manages the entire acid gas volume. There is no flaring. No cutback in upstream units. The SRU operates smoothly with higher furnace temperature and complete BTEX destruction. After maintenance, the idle train restarts on air and the plant returns to two-train oper- ation. Table 2 shows the required important parameters.
The ASU remained online at minimum load in air mode. When the switch to oxygen mode was needed, the ASU sim - ply raised production to ensure there was no warm-up delay. Outcomes and benefits The selected plant hardware design parameters based on the ‘worst case’ considerations from the above two oper- ating scenarios and as listed in Tables 1 and 2 are summa- rised in Table 3: • No ‘actual’ standby SRU was required. • The plant maintained more than 99.9% sulphur recovery in both modes. • The plant achieved emission targets in both modes. • Furnace temperature was high enough to destroy all con- taminants without using fuel gas.
Catalytic stages
Reaction furnace
O
Vent gas
Condensers
Liq. sulphur to degassing
AGE ABS. column
Quench column
TGT ABS. column
To Atm.
Catalytic stages
Reaction furnace
O
TGTU reactor
Incinerator
Feed gas
Liquid sulphur
Rich solvent to regen column
Condensers
Regen column
Rich solvent from TGT ABS column
Vent gas
Storage section
Liquid sulphur
Degassing section
Figure 2 Overall schematic diagram of the hybrid sulphur plant
70
PTQ Q4 2026
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