Reactor Cascade: Kymograph & Response Chart

What is a Reactor Cascade?

A reactor cascade consists of multiple continuous stirred-tank reactors (CSTRs) arranged in series. Each reactor processes the output from the previous one, allowing for complex chemical transformations to be achieved step-by-step.

In this simulation, you can model such cascades using ordinary differential equations (ODEs), which describe how the concentration of reactants and products changes over time within each tank.

The Mass-Balance Equations

The core of the simulation involves solving mass-balance ODEs, which track the rate of change of species concentrations in each reactor. These equations are based on the principle that the rate of change of concentration equals the net flow rate into or out of the tank minus any production or consumption within it.

For a CSTR with inlet and outlet flows, the mass-balance equation can be expressed as dC/dt = (F/V)(Ci - C) + r(C), where C is the concentration, F is the volumetric flow rate, V is the volume of the tank, Ci is the inlet concentration, and r(C) represents any reaction term.

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Visualizing Reactor Dynamics

The kymograph provides a 2D visualization of how concentrations change over time across all reactors in the cascade. Each vertical line represents one reactor, and its height corresponds to the concentration at that point.

The response chart shows the concentration changes over time for each reactor individually, allowing you to observe the propagation of disturbances through the system.

Analyzing Disturbances

By applying step, pulse, or sinusoidal feed disturbances, you can study how these affect the steady-state operation and transient behavior of the cascade.

The exact closed-form tanks-in-series curve allows for direct comparison with your simulated results, providing insights into the accuracy of your model.

Frequently asked questions

What are the advantages of using CSTRs in series?

Using CSTRs in series can achieve higher conversion rates and better control over reaction conditions compared to a single reactor, as each reactor operates under different steady-state conditions.

How does changing the number of tanks affect the system's performance?

Increasing the number of tanks generally improves the overall conversion efficiency but also increases the complexity and cost of the process. More tanks can better handle complex reactions with multiple steps.

Why is it important to consider the residence time in each tank?

The residence time determines how long a reactant spends in the reactor, which directly affects its conversion rate and product distribution. Optimal residence times are crucial for maximizing yield and minimizing side reactions.

Can this simulation be used to optimize reactor design parameters?

Yes, by adjusting the number of tanks and their residence times, you can optimize the reactor cascade to achieve desired conversion rates and product concentrations while minimizing energy consumption and operational costs.

Try it live

Everything above runs in your browser — open Reactor Cascade: Kymograph & Response Chart and change the parameters while it is running. Nothing is installed, nothing is uploaded, the whole model lives in one tab.

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