PFR Design Calculator

A Plug Flow Reactor (PFR) is a type of chemical reactor where reactants flow continuously through a tube and react as they move along its length — used in industrial chemical processes to achieve a target conversion. Enter your feed concentration (CA0), volumetric flow rate (v0), target conversion, reaction order, and rate constant (k) into the PFR Design Calculator to find the required reactor volume. Secondary outputs include space time (τ), exit concentration (CA), molar feed rate (FA0), and actual conversion.

mol/L
L/min
%
1/min
L

Leave blank to calculate, or enter to find other parameters

Results

Required Reactor Volume

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Space Time (τ)

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Exit Concentration (CA)

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Molar Feed Rate (FA0)

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Actual Conversion

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Frequently Asked Questions

What is the difference between a PFR and CSTR reactor?

A Plug Flow Reactor (PFR) has no radial mixing and concentration changes along the reactor length, while a Continuously Stirred Tank Reactor (CSTR) has uniform concentration throughout. PFRs typically require less volume for the same conversion.

How do I calculate the space time for a plug flow reactor?

Space time (τ) is calculated as reactor volume divided by volumetric flow rate (τ = V/v₀). It represents the theoretical residence time of fluid in the reactor.

What reaction orders can this calculator handle?

This calculator supports zero-order, first-order, and second-order reactions. The design equations and volume calculations are adjusted automatically based on the selected reaction order.

How does conversion affect reactor volume requirements?

Higher conversion requires larger reactor volume or longer residence time. The relationship is non-linear, especially for higher-order reactions where achieving the last 10-20% conversion requires significantly more volume.

What units are used in the PFR design calculations?

The calculator uses mol/L for concentrations, L/min for flow rates, L for volumes, and 1/min for rate constants. Results include space time in minutes and conversion as a percentage.

Can I use this calculator for gas-phase reactions?

Yes, but ensure you account for pressure drop and density changes. For ideal gas reactions, you may need to convert between molar and volumetric flow rates using the ideal gas law.

What is the design equation for a plug flow reactor?

The PFR design equation is V = FA0 ∫(dX/-rA) where V is volume, FA0 is molar feed rate, X is conversion, and -rA is the reaction rate. The integral depends on the reaction kinetics.