Thank you for suggestion Rob. I created a journal named "save_monitors.jou" that may help future viewers displaying and saving their monitor plots. This journal has the following structure (I am only showing a snippet here for illustration purposes):
plot/residuals yes yes yes yes yes yes yes
/display/save-picture "monitors/residuals.png"

/solve/report-plots/plot fan_inlet_totalp-rplot /display/save-picture "monitors/fan_inlet_totalp-rplot.png"
The above commands make Fluent to display and save the residuals plot (the various "yes" are required to plot all the types of residuals) and the report plot "fan_inlet_totalp-rplot" in the folder "monitors". Similar commands may be added to display more plots. The user may make Fluent to read the journal by using the command file rj save_monitors.jou .