Reactor Sizing Calculator (CSTR vs PFR)

• •Use the Reactor Sizing Calculator (CSTR vs PFR) when solving homework or exam problems that require quick numerical verification of your hand calculations — instant feedback helps identify arithmetic errors before they propagate.
• •Use it during the early design phase to rapidly iterate on parameters and narrow down feasible configurations before committing time to detailed finite element simulations or full design packages.
• •Use it when reviewing a colleague's calculation or checking a vendor's data sheet for plausibility — a quick sanity check can prevent costly downstream errors.
• •Use it to generate reference data for a technical report or presentation without manual computation, ensuring consistent, reproducible numbers throughout the document.
• •Use it in the field when a quick estimate is needed and a full engineering software package is not available.

The Reactor Sizing Calculator (CSTR vs PFR) is a precision engineering calculation tool designed for students, engineers, and technical professionals. CSTR and PFR sizing for 1st and 2nd order reactions: required volume, Levenspiel plot with shaded areas, and volume ratio comparison All calculations are performed using established engineering formulas from the relevant scientific literature and standards. Inputs support both metric (SI) and imperial unit systems, with unit conversion handled automatically — simply select your preferred unit from the dropdown next to each field. Results are computed instantly in the browser without sending data to a server, ensuring both speed and privacy. This calculator is intended as a supplementary tool for learning and design exploration; always verify results against authoritative references for safety-critical applications.

Reactor sizing determines the volume needed for a chemical reactor to achieve a target conversion under specified conditions. The two idealized reactor types are: CSTR (Continuous Stirred-Tank Reactor) — perfectly mixed, reactor contents uniform at outlet conditions. Design equation: V = F_A₀·X_A / (−r_A), where F_A₀ is molar flow rate of A entering, X_A is fractional conversion, and −r_A is reaction rate at outlet conditions. PFR (Plug-Flow Reactor) — plug flow with no back-mixing, reactants flowing through the reactor with conversion increasing continuously. Design equation: V = F_A₀·∫₀^X_A dX_A/(−r_A). For first-order reactions (−r_A = k·C_A) in constant-density systems, these simplify: CSTR needs more volume than PFR for the same conversion; PFR is more efficient for orders > 0. Second-order reactions: CSTR needs much more volume (ratio grows with order). Zero-order reactions: CSTR and PFR need equal volume. For 90% conversion of a first-order reaction, a CSTR needs 10× more volume than a PFR; for a second-order reaction, it needs about 20× more. Real reactors fall between ideal CSTR and PFR; residence time distribution characterizes deviation from ideal. The calculator handles sizing of both CSTR and PFR for 1st and 2nd order reactions and plots Levenspiel diagrams.

• •Batch reactor to continuous process conversion: size a CSTR or PFR equivalent to a successful batch process with the same throughput and conversion.
• •Pharmaceutical manufacturing: size continuous reactors for intermediate synthesis steps to replace batch processes, improving efficiency and quality control.
• •Petrochemical cracking: steam crackers and catalytic crackers are designed as PFR-type reactors for maximum conversion in minimum volume.
• •Biochemical processing: fermenter design uses CSTR models with growth kinetics for microbial and enzymatic reactions.
• •Wastewater treatment: bioreactors for aerobic and anaerobic digestion use CSTR-in-series or PFR models depending on target organism and conditions.