Inorganic Chemical Manufacturing, Sulfuric Acid & Emissions Control
Contact Process Sulfuric Acid (DCDA) Tonnage & SO2 Slip Formula
Calculate Sulfur-Burner SO2 Generated (t/d), 100%-Basis H2SO4 Equivalent (t/d), Commercial 98 wt% Acid Output (t/d), and Unconverted Stack SO2 Emissions (t/d).
Upgrading 98.0% single-contact to 99.7% Double-Contact Double-Absorption cuts SO2 pollution 6.7x!
In Contact-Process sulfuric acid plants burning molten elemental sulfur (S + O2 -> SO2, MW 32 -> 64) and oxidizing SO2 over Vanadium Pentoxide V2O5 catalyst beds (SO2 + 0.5 O2 -> SO3, absorbed into 98 wt% H2SO4, MW 98), 1.00 ton of pure sulfur theoretically yields 64 / 32 = 2.00 tons of SO2 and 98 / 32 = 3.0625 tons of 100% H2SO4 (or 3.0625 / 0.98 = 3.125 tons of commercial 98 wt% acid)! Shifting equilibrium via an inter-pass absorber tower in Double-Contact Double-Absorption (DCDA) lifts SO2 conversion from 98.0% to 99.7%—barely nudging acid output (+1.7%), yet slashing unconverted tail-gas SO2 emissions by 85%!
Verify on a 320.0 t/d Molten-Sulfur DCDA Plant (10,000 kmol/d S, B2) at SO2_Conversion = 0.997 (99.7%, B3) and Commercial_Acid_Strength = 0.98 (98.0 wt% H2SO4, B4): Burner SO2 Generated equals 320 * 2 = 640.00 t/d (E2), Pure 100% H2SO4 Produced hits (320 / 32) * 0.997 * 98 = 977.06 t/d (E3), Commercial 98% Acid Tonnage equals 977.06 / 0.98 = 997.00 t/d (E4), and Unconverted Tail-Gas SO2 Slip is just 640 * (1 - 0.997) = 1.92 t/d (E5)!
| DCDA Sulfuric Acid KPI (320 t/d Sulfur, 99.7% DCDA Conv, 98 wt% Acid) | Formula | Verified Output |
|---|---|---|
| Sulfur Burner SO2 Generated (t/d) | Sulfur_t_d * (64 / 32) | 640.00 t/d |
| 100%-Basis Pure H2SO4 (t/d) | (Sulfur_t_d / 32) * Conv * 98 | 977.06 t/d (960.40 @ 98% single) |
| Commercial 98 wt% Acid (t/d) | Pure_100Pct_H2SO4 / Acid_WtFrac | 997.00 t/d (980.00 @ 98% single) |
| Unconverted Stack SO2 Slip (t/d) | Burner_SO2_t_d * (1 - Conv) | 1.92 t/d (12.80 @ 98% single!) |
Commercial Sulfuric Acid Output & Tail-Gas SO2 Slip Formula
Validate Sulfur_Burned > 0, SO2_Conversion in [0.90, 0.9999], and Acid_WtFrac in [0.93, 1.0]!
=LET(sf_t, B2, cv_x, B3, ac_w, B4, IF(OR(sf_t <= 0, cv_x < 0.9, cv_x > 0.9999, ac_w < 0.93, ac_w > 1), "Invalid Acid Plant Input", ROUND(((sf_t / 32) * cv_x * 98) / ac_w, 2)))Legacy Single-Absorption Environmental Penalty Check (Set Conversion = 0.98)
Drop SO2_Conversion B3 from 0.997 (DCDA) to 0.980 (legacy single-absorption): Commercial 98% Acid E4 dips slightly from 997.00 to 980.00 t/d, while Unconverted Stack SO2 Emissions E5 surge 6.67x from 1.92 t/d to 12.80 t/d!
=IF(ISTEXT(E4), E4, ROUND((B2 * 2) * (1 - B3), 2))Try the example
Use the original values or change them to test your understanding.