1 04 Material Balance 1

Department of hemical Engineering University of the Philippines Diliman

Material Balances 1 

Outline  !  The

Balance Equation 

!  Mass

Balance Analysis 

! 

 

Tie Component !  Degree of Freedom Analysis  !  Mass

Balance Calculations – Single Unit 

!  Multiple

Unit Balances 

2

The Balance Equation  The Balance Equation  Mass Balance Analysis   Tie Component  Degree of Freedom Analysis  Mass Balance Calculations Single Unit  – Multiple-Unit Balances 

3

The Balance Equation  The Balance Equation 

!  Conservation ! 

Mass Balance Analysis   Tie Component  Degree of Freedom Analysis  Mass Balance Calculations Single Unit  – Multiple-Unit Balances 

! 

Laws 

Mass (except in nuclear reactions)  ! 

Moles are NOT conserved when there are reactions! 

! 

Volume is generally NOT conserved 

Energy (1st Law of Thermodynamics) 

!  For

any conserved property,  In – Out + Generation = Accumulation 

! 

IN: sum of all flow rates into the system 

! 

OUT:: sum of all flow rates going out of the system  OUT

! 

GEN: formation or consumption within the system 

!  ACC:

net rate of change of the property property in the system (zero at steady-state)  4

The Balance Equation  The Balance Equation 

!  Di"erential !  Terms

are in rate form  !  Usually for continuous processes 

Mass Balance Analysis   Tie Component  Degree of Freedom Analysis  Mass Balance Calculations Single Unit  – Multiple-Unit Balances 

Balance 

! 

 

Integral Balance !  Describes two points in time  !  Terms are in amounts   !  Usually for batch processes 

!  Basic !  For

Rules 

total mass, GEN = 0   !  For non-reacting species, GEN = 0  !  For steady-state, ACC = 0  5