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| Scenario | Mode | Key inputs | Expected ethylene (t/day) |
|---|---|---|---|
| Ethane-rich cracker | Yield-based | Feed 50,000 kg/h, weight yield 30% | 360.000 |
| Analyzer snapshot | Composition-based | Outlet 2,500 kmol/h, ethylene 18.5% | 312.3 |
| Reactor performance | Conversion & selectivity | Ethane 1,800 kmol/h, conversion 65%, selectivity 85% | 663.0 |
Ethylene rate often starts from a mass feed and a reported overall yield. For ethane-rich crackers, a 28–34 wt% ethylene yield is common when operating severity targets high ethylene and low liquids. If you enter 50,000 kg/h feed and 30% weight yield, the calculator returns 15,000 kg/h ethylene and converts it using MW 28.0532 g/mol to kmol/h for consistent mass–mole reporting.
When plant historians track ethane conversion and selectivity to ethylene, production is best estimated on a stoichiometric basis. Per-pass conversion typically ranges 55–75%, while selectivity can exceed 80–90% when residence time and coil outlet temperature are optimized. The conversion method multiplies ethane feed by conversion and selectivity, giving an ethylene molar rate that can be compared directly with analyzer totals.
Gas chromatographs provide quick composition snapshots, but they are only as good as the total flow basis. Using total cracked-gas flow (kmol/h) and ethylene mole fraction (often 15–25 mol% in mixed cracked gas), the composition mode estimates ethylene production without assuming yield. If total flow is available as Nm³/h, the tool converts using a selectable Nm³ per kmol factor, letting you align with your site’s reference conditions.
Hourly production alone rarely matches business reporting. The calculator annualizes with hours/day, days/year, and an additional uptime factor to represent unplanned downtime. For example, 330 days/year and 92% uptime implies 7,286 effective hours on a 24 h/day schedule. This supports realistic budget volumes, turnaround planning, and capacity commitments.
Use the three modes to triangulate performance: yields for planning, conversion/selectivity for furnace diagnostics, and composition for mass-balance reconciliation. Track sensitivity: a 1% absolute change in yield on 50,000 kg/h feed shifts ethylene by 500 kg/h, or about 12 t/day. Pair results with energy intensity, coil pressure drop, and quench performance to identify bottlenecks and sustain stable operation. To reduce uncertainty, keep units consistent, verify whether yields are on fresh feed, hydrocarbon feed, or dry basis, and document how recycle and purge streams are treated. When comparing months, normalize to the same product slate and reporting conditions to avoid misleading trend conclusions during audits.
Use Yield-based when you know feed rate and overall ethylene yield. Use Conversion & selectivity when you track ethane conversion and ethylene selectivity. Use Composition-based when you have total outlet flow and ethylene mole fraction from an analyzer.
It is the reference normal-volume occupied by one kmol of gas at your chosen standard conditions. The default 22.414 Nm³/kmol corresponds to 0°C and 1 atm. If your site uses 15°C or 20°C, update the factor to match.
Uptime is treated as additional unplanned availability on top of the scheduled hours/day and days/year you enter. Effective annual tons are calculated from the hourly ethylene rate multiplied by annual scheduled hours, then multiplied by uptime as a decimal.
The calculator is a steady-state rate estimator. You can represent multiple furnaces by entering the combined feed or combined outlet flow. Recycle and purge effects are included only if they are already reflected in your chosen basis (yield, conversion/selectivity, or outlet flow).
They can differ because yield is often reported on fresh-feed mass, while selectivity is defined on converted moles of reactant. Analyzer totals may include diluents or steam. Align bases, moisture corrections, and boundary streams before comparing methods.
Confirm whether your feed input is per hour, day, or year and select the matching unit. For composition mode, ensure outlet flow and ethylene fraction are on the same dry or wet basis. Review the KPI panel, then export CSV or PDF.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.