Space Time Formula:
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Definition: Space time (τ) is the time required to process one reactor volume of feed under specified conditions, accounting for reactant recycle in a second-order reaction system.
Purpose: This calculation helps chemical engineers design reactors with recycle streams for second-order reactions, optimizing reactor size and performance.
The calculator uses the formula:
Where:
Explanation: The formula accounts for the effect of reactant recycle on the reaction kinetics and the required residence time in the reactor.
Details: Accurate space time calculation ensures proper reactor sizing, optimal conversion rates, and efficient use of recycled materials in chemical processes.
Tips: Enter the recycle ratio (R), initial concentration (C₀), final concentration (C_f), and rate constant (k''). All concentration values must be positive with C₀ > C_f.
Q1: What is a typical recycle ratio range?
A: Recycle ratios typically range from 0 (no recycle) to 5 or more, depending on process requirements.
Q2: Why is space time important in reactor design?
A: Space time directly relates to reactor volume needed for a given feed rate and desired conversion.
Q3: How does recycle affect space time?
A: Recycle generally increases required space time due to dilution of fresh feed with reacted material.
Q4: What units should be used for concentrations?
A: Use consistent molar concentration units (typically mol/m³) for all concentration values.
Q5: When is this calculation not applicable?
A: This formula is specific for second-order reactions with constant-density systems and perfect mixing.