# Performing Non - Reactive Mass and Energy Balances (NRB)

### Performing Non - Reactive Mass and Energy Balances

Now that we know how to write the equations that will get us started for balances, we need to worry about when they are useful.How do we know when to write these equations, or how many we need ?

• Perform single - unit mass balances
• Perform a degree - of - freedom analysis for a single - unit mass balance process
• Do the calculations suggested in the degree - of - freedom analysis

Real processes often include more than one process unit.How do we handle arbitrary numbers of units ? arbitrarily complex arrangements of those units ?

• Identify relevant sub - systems within a multi - unit process on which to perform a degree - of - freedom analysis(and subsequently do the required calculations)
• Perform mass balances(degree - of - freedom plus calculations) for systems with recycle, bypass, and purge streams

Energy balances can be used as an additional equation in mass balances.

• Simplify and solve the General Energy Balance for non - reactive systems