Inputs
Example Data Table
| Case | Flow (Nm³/h) | H₂S (mol%) | CO₂ (mol%) | Efficiency (%) | Margin (%) | Availability (%) | Trains |
|---|---|---|---|---|---|---|---|
| A | 1200 | 70 | 25 | 96.5 | 10 | 95 | 1 |
| B | 2600 | 55 | 40 | 97.8 | 12 | 92 | 2 |
| C | 800 | 85 | 10 | 95.0 | 8 | 96 | 1 |
Formula Used
- Total molar flow: ṅ_total (kmol/h) = Q (Nm³/h) ÷ V̄ (Nm³/kmol)
- H₂S molar flow: ṅ_H2S = ṅ_total × (H₂S% ÷ 100)
- Theoretical sulfur: ṁ_S (kg/h) = ṅ_H2S × 32.065
- Convert to tonnes/day: S_theoretical (t/d) = ṁ_S × 24 ÷ 1000
- Recovered sulfur: S_recovered = S_theoretical × (η ÷ 100)
- Design nameplate: S_design = S_recovered × (1+margin) ÷ availability
How to Use This Calculator
- Enter the acid gas flow at your chosen standard reference conditions.
- Input H₂S mol% and CO₂ mol% from laboratory or process data.
- Select the standard molar volume that matches your flow basis.
- Set recovery efficiency, design margin, availability, and number of trains.
- Click Calculate to view results above the form.
- Use Download CSV or Download PDF to save the report.
Technical Article
1) Why sulfur recovery capacity matters
Sulfur recovery units are typically sized in tonnes per day of elemental sulfur. Capacity links the upstream acid-gas loading to downstream storage, logistics, and environmental compliance. A practical sizing check starts with standard volumetric flow (Nm³/h), converts to kmol/h using a selected standard molar volume, and then applies the expected overall recovery efficiency.
2) Capacity data inputs that drive results
In most sour-gas and refinery applications, H₂S mol% is the dominant variable because it directly determines the theoretical sulfur yield. CO₂ and inert fractions influence hydraulics and thermal balance, but they do not contribute sulfur mass. Typical design efficiencies can range from about 94% to 99.8% depending on reaction staging and tail-gas treatment.
3) Conversions and engineering units
Standard molar volume selection is essential for consistent calculations. Common references include 22.414 Nm³/kmol (0°C), 23.645 Nm³/kmol (15°C), and 24.465 Nm³/kmol (25°C). With 1 kmol of H₂S producing approximately 1 kmol of sulfur, the sulfur mass basis uses 32.065 kg per kmol of sulfur. The calculator reports tonnes/day for capacity and tonnes/year for planning.
4) Margin, availability, and train selection
Capacity should reflect uncertainty and uptime. A 5–15% design margin is common for feed variability, catalyst aging, and fouling. Availability factors (for example 90–98%) scale the nameplate upward so annual production targets remain achievable. Multiple trains improve maintainability; dividing total nameplate across trains also supports phased expansions and turndown requirements.
5) Using results for construction planning
Once the design capacity is known, teams can size sulfur pits, granulation, loading, and emissions monitoring. Daily sulfur rates inform truck or rail dispatch cycles, while annual tonnage supports storage days-of-coverage calculations. Use the report exports to document assumptions during constructability reviews, procurement packages, and commissioning checklists.
FAQs
1) Does CO₂ affect sulfur tonnes per day?
CO₂ does not create sulfur mass, but it can affect hydraulics, temperatures, and equipment sizing. Keep CO₂ in your basis for realistic composition tracking and design discussions.
2) Which standard molar volume should I use?
Use the same reference as your flow measurement basis. If your flow is stated at 15°C, select 23.645 Nm³/kmol. Consistency is more important than the specific reference.
3) What recovery efficiency should I enter?
Use an overall value that reflects your expected configuration. For preliminary checks, 96–98% is common. If you have tail-gas treatment, efficiencies can be higher.
4) Why does lower availability increase nameplate?
If the unit is down more often, it must produce more when operating to meet the same annual target. The calculator scales capacity by dividing by the availability fraction.
5) What is a reasonable design margin?
Many projects apply 5–15% depending on feed variability and uncertainty. Use higher margins when upstream composition is unstable or when future debottlenecking is expected.
6) How should I choose the number of trains?
Two trains can improve maintenance flexibility and reduce single-point risk. For small capacities, one train is typical. For larger capacities, multiple trains can simplify turnarounds.
7) Are these results suitable for final design?
Treat them as a screening and documentation tool. Final design should include detailed assays, pressure/temperature corrections, reaction heat balance, equipment constraints, and vendor guarantees.