Calculator
Example data table
| Run | Inlet basis | Outlet basis | Residence time (s) | Conversion (X) | Conversion (%) |
|---|---|---|---|---|---|
| Baseline | 2.500000 | 0.650000 | 45 | 0.740000 | 74.000 |
| Higher temperature | 2.500000 | 0.450000 | 45 | 0.820000 | 82.000 |
| Lower residence | 2.500000 | 0.900000 | 25 | 0.640000 | 64.000 |
Formula used
- Conversion: X = (F_in − F_out) / F_in
- Percent conversion: X% = 100 × X
- Conversion rate: r_X = X / τ where τ is residence time in seconds
- Concentration method basis: uses F ∝ C × v for inlet and outlet
How to use this calculator
- Select an input method that matches your measurements.
- Enter inlet and outlet values for reactant A.
- Optionally enter residence time to compute a rate.
- Press Submit to view results above the form.
- Use CSV or PDF export to save the run summary.
Conversion meaning for reactors
Conversion X is the fraction of limiting reactant consumed from inlet to outlet. In continuous operation, X often ranges from 0.40 to 0.95 depending on kinetics, mixing, and catalyst activity. For example, inlet molar flow 2.50 and outlet 0.65 gives X = 0.74, so 74% of reactant A is converted.
Picking the best input data
Use molar flow when a flowmeter and composition are available, mass flow when weighing or coriolis data is primary, and concentration × volumetric flow when density or expansion changes v. With CA0 = 1.20 and v0 = 0.50, inlet basis is 0.60. With CA = 0.30 and v = 0.55, outlet basis is 0.165, so X = 72.5%.
Residence time and intensity
Residence time τ links performance to throughput and reactor volume. Holding conversion constant while reducing τ demands faster reaction or better mass transfer. With X = 0.74 and τ = 45 s, the conversion rate is 0.01644 s⁻1. If τ drops to 25 s, an outlet of 0.90 gives X = 0.64 and a rate of 0.02560 s⁻1. Use this rate for quick comparisons, not as a kinetic constant.
Data quality and engineering checks
Conversion is sensitive to sampling alignment, analyzer lag, and sensor drift. A 2% bias in outlet measurement can shift X by several points when conversion is high. Confirm steady state by repeating outlet readings and verifying inlet composition stability. If outlet exceeds inlet, treat it as a data integrity flag, then review calibration, units, and timestamps. For multiphase systems, ensure the sample represents the bulk.
Using results for optimization and reporting
Track each run with a scenario label like “Higher temperature” or “Lower residence.” When testing setpoints, aim to improve conversion without exceeding heat removal, pressure drop, or selectivity constraints. A small conversion gain can be valuable when feed cost is high, but it may increase byproduct formation. Exported CSV supports trending across runs, while PDF is useful for batch records, shift handover, and audit trails. Include catalyst age and inlet temperature to explain shifts in conversion over time. Compare only runs using the same basis, and record τ in seconds for consistent rate reporting.
FAQs
1) What is the difference between conversion and conversion rate?
Conversion is the fraction of reactant consumed between inlet and outlet. Conversion rate here is X divided by residence time in seconds, giving a normalized intensity metric for comparing runs with different τ.
2) Which input method should I use for gases with expansion?
Use the concentration × volumetric flow method because it allows different inlet and outlet volumetric flow rates. This better reflects changing density or molar volume, especially at high temperature or significant pressure drop.
3) Why does the calculator prevent outlet values above inlet?
For a limiting reactant basis, outlet exceeding inlet implies inconsistent units, sampling mismatch, analyzer lag, or data entry errors. Treat it as a quality check before making process decisions based on the computed value.
4) Can I compare two scenarios with different units?
You can, but only if the inlet and outlet are consistent within each scenario. For comparisons, keep the same basis and units across runs; otherwise, trends may reflect unit changes rather than reactor performance.
5) How should residence time be entered for batch-like tests?
Enter the effective contact time that best represents the reacting volume and flow path, then select the correct unit. For non-ideal systems, use a measured mean residence time rather than a nominal volume/flow estimate.
6) Why export both CSV and PDF?
CSV is ideal for plotting and statistical comparisons across many runs. PDF captures a fixed snapshot with context and timestamps, useful for shift handovers, audits, and attaching to engineering reports.