A simple plug flow reactor figure using Python (matplotlib)

plot_PFR.py

# coding: utf-8
"""
Plug flow reactor figure created with Python

This example displays a simple representation of a plug flow reactor (PFR)
by means of matplotlib API. A full list of artists and the documentation is
available at http://matplotlib.org/api/artist_api.html.

Copyright (c) 2015, Francisco J. Navarro-Brull
                    http://CAChemE.org
MIT License

More Chemical Engineering examples can be found here:
https://github.com/cacheme/learn
"""

import matplotlib.pyplot as plt
from matplotlib.patches import Ellipse, Rectangle, Arrow

# In Python comments are indicated with "#"
# Until now we have just imported the libraries to plot the PFR

fig, axes = plt.subplots()

reactor_length = 3    # [m]
reactor_diameter = 1  # [m] 

arrow_lenght = 1  # [m]

# Let's begin with the arrow representing the outlet
arrow_outlet = Arrow(reactor_length, reactor_diameter/2,  # x, y (coordinates)
                     arrow_lenght, 0, width=0.1,          # dx, dy
                     facecolor="black")                   # color options
axes.add_patch(arrow_outlet)  # adds the path to the plot

# Now we create and plot elliplse representing the end of the cillinder
ellipse_outlet = Ellipse((reactor_length,reactor_diameter/2),   # x, y (coordinates)
                          reactor_diameter/2, reactor_diameter, # width, height
                          facecolor="grey", edgecolor="black")  # color options
axes.add_patch(ellipse_outlet)  # adds the patch to the plot

# Create and plot the tube as rectangle 
rectangle = Rectangle((0, 0),                            # x, y (coordinates)
                     reactor_length, reactor_diameter,   # width, height 
                     facecolor="grey", edgecolor="none") # color options 
axes.add_patch(rectangle)  # adds the patch to the plot

# Again we create an ellipse but this time at the inlet
ellipse_inlet = Ellipse((0,reactor_diameter/2),                # x, y (coordinates)
                        reactor_diameter/2, reactor_diameter,  # width, height
                        facecolor="grey", edgecolor="black")   # color options
axes.add_patch(ellipse_inlet) # adds the patch to the plot

# And finally the inlet arrow
arrow_inlet = Arrow(-arrow_lenght, reactor_diameter/2,  # x, y (coordinates)
                     arrow_lenght, 0, width=0.1,        # dx, dy, arrow width
                     facecolor="black")                 # color options
axes.add_patch(arrow_inlet)  # adds the patch to the plot

plt.axis('equal') # forces the same grid space between axes
plt.axis('off')   # removes al the ticks and axes (comment this line to better understand the code above)

# axes.set_xlim([-2,4])  # fixes the x axes
# axes.set_ylim([-1,1])  # fixes the y axes

plt.show()  # shows the figure