Hydrogen sulfided(H2S) is a byproduct of processing natural gas or refining high-sulfur crude oils. The Sulfur Recovery Process (mostly known as Clause Process) is to recover elemental sulfur from gaseous hydrogen sulfide. The Claus process involves burning one-third of the H2S with air in a reactor furnace to form sulfur dioxide (SO2):
2H2S + 3O2 → 2SO2 + 2H2O
The remaining uncombusted two-thirds of the hydrogen sulfide undergoes Claus reaction (reacts with SO2):
2H2S + SO2 ↔ 3S + 2H2O
The process consists of multistage catalytic oxidation of gaseous hydrogen sulfide, each catalytic stage consists of a gas reheater, a catalyst chamber, and a sulfur condenser.
Critical Control of Process Gas
To maximize sulfur recovery requests precisely control of sulfur ratio H2S/SO2=2:1 in tail gas, the measurement is input as feedback to determine dosage of raw acid gas and air.
Detect Hydrogen(H2) outlet of the quenching tower to monitor the hydroteating process of Claus tail gas.
Detect sulfur dioxide(SO2) and oxygen(O2) downstream of steam boiler and on emission stack to ensure environmental compliance.
Challenge of Instrumentation
The sulfur vapor flows through conventional non-heated sampling system is inevitably condensed and problematic to block sampling line. The corrosive, explosive and toxic flue gas with high moisture contained allows only the most robust and reliable sampling system. The sulfur ratio analyzer is required to be free of cross interference from sulfur vapor(Sv) and byproduct sulfur compounds(CS2, COS).
All-route heat tracing from probe, sampling line through to gas chamber, enhanced with automatic hot steam back flush, effectively prevents blockage and corrosion to the sampling system. FPI’s sulfur ratio and emission analyzers using diode array spectrometer and DOAS algorithm minimize interference from Sv, CS2, COS, moisture and dust.
Raw acid gas
Claus tail gas
Quench tower top gas
NOTES: Listed are typical data FPI experienced and backed by field references. Alternate gases and ranges may be available or customizable on request.