Claus Sulfur Recovery (Thermal Stage) Calculator
Calculate Claus reaction furnace adiabatic flame temperature, theoretical 1/3 oxidation combustion air demand, waste heat boiler (WHB) steam generation, and thermal H2S conversion per GPSA Section 22.
Acid Gas Feed & Composition
Combustion Air & WHB Operating State
Furnace Flame & Sulfur Production
Recommended Tools & Equipment
Tested hardware and components for high reliability
Frequently Asked Questions
What occurs inside the Claus reaction furnace thermal stage?
The thermal stage is the heart of the Claus process. High-pressure acid gas is fed to a refractory-lined furnace where exactly one-third of the H2S is combusted with air to SO2 (H2S + 1.5 O2 -> SO2 + H2O). The remaining two-thirds of the unburned H2S reacts with the newly formed SO2 at temperatures above 2000°F (1100°C) to yield elemental sulfur vapor (2 H2S + SO2 <-> 3/2 S2 + 2 H2O), achieving 65% to 72% overall sulfur conversion.
Why must the reaction furnace flame temperature be maintained above 2100°F (1150°C)?
If the acid gas contains aromatic hydrocarbons (BTEX: benzene, toluene, ethylbenzene, xylene) or ammonia, operating below 2100°F fails to completely crack these compounds. Uncracked BTEX forms sticky carbonaceous soot and polymer gums that deposit onto downstream alumina catalyst beds, destroying catalytic activity within months.
What is the role of the Waste Heat Boiler (WHB) in an SRU?
Gases exit the reaction furnace at 2200°F to 2600°F containing molten sulfur vapor and enormous thermal energy. The Waste Heat Boiler rapidly quenches these gases to ~550°F (290°C), freezing the high-temperature sulfur equilibrium to prevent recombining back into H2S while producing vast quantities of 400-600 psig saturated high-pressure steam for plant utility power.