CSTR Design Calculator

A CSTR (Continuously Stirred Tank Reactor) is a chemical reactor where reactants are continuously fed into the reactor while products are continuously removed. The contents are well-mixed, ensuring uniform concentration throughout the reactor volume.

Residence time (τ) is the average time a reactant spends in the reactor. Higher residence times generally lead to higher conversion rates, but the relationship depends on the reaction kinetics and may reach diminishing returns.

CSTRs have uniform concentration throughout due to perfect mixing, while PFRs (Plug Flow Reactors) have concentration gradients along the reactor length. For the same conversion, CSTRs typically require larger volumes than PFRs for most reaction orders.

Reaction order significantly impacts the CSTR design equation. Zero-order reactions have linear kinetics, first-order reactions follow exponential decay, and second-order reactions have more complex relationships affecting required reactor volume.

Optimal CSTR volume depends on desired conversion, feed flow rate, reaction rate constant, reaction order, and economic considerations. Higher conversions require larger volumes, but operating costs increase accordingly.

Residence time (τ) is calculated as reactor volume divided by volumetric flow rate (τ = V/v₀). This represents the theoretical mean time a molecule spends in the reactor under steady-state conditions.

The basic CSTR design equation is V = FA0 × X / (-rA), where V is volume, FA0 is molar feed rate, X is conversion, and (-rA) is the reaction rate. The specific form depends on the reaction kinetics and order.