Page 117 - Chemical engineering design

FUNDAMENTALS OF ENERGY BALANCES
INPUT THE NUMBER OF FEED STREAMS
?2
FOR FEED STREAM 1 INPUT STREAM TEMP AND NUMBER OF COMPONENTS 97
? 323, 1
FOR EACH COMPONENT, INPUT THE COMPONENT NUMBER AND FLOW-RATE
NEXT COMPONENT
? 5, 100
STREAM SENSIBLE HEAT = 4000 kJ/h
FOR FEED STREAM 2 INPUT STREAM TEMP AND NUMBER OF COMPONENTS
? 288, 2
FOR EACH COMPONENT, INPUT THE COMPONENT NUMBER AND FLOW-RATE
NEXT COMPONENT
? 3, 11.15
NEXT COMPONENT
? 4, 41.94
STREAM SENSIBLE HEAT = -15,484.61 kJ/h
INPUT NUMBER OF PRODUCT STREAMS
?1
FOR PRODUCT STREAM 1 INPUT STREAM TEMP AND NUMBER OF COMPONENTS
? 1500, 4
FOR EACH COMPONENT, INPUT THE COMPONENT NUMBER AND FLOW-RATE
NEXT COMPONENT
? 1, 7.29
NEXT COMPONENT
? 2, 4.0
NEXT COMPONENT
? 3, 1.97
NEXT COMPONENT
? 4, 41.98
STREAM SENSIBLE HEAT = 2319620 kJ/h
INPUT THE NUMBER OF REACTIONS AND PHASE CHANGES
?2
FOR EACH REACTION OR PHASE CHANGE INPUT THE HEAT OF REACTION
OR THE LATENT HEAT, kJ/kmol; AND QUANTITY INVOLVED kmol/h
REMEMBER: HEAT ENVOLVED:POSITIVE; HEAT ABSORBED:NEGATIVE
NEXT REACTION/PHASE CHANGE: INPUT VALUES
? +39540, 100
NEXT REACTION/PHASE CHANGE: INPUT VALUES
? -350, 100
COOLING REQUIRED = -1587896 kJ/h
REPEAT CALCULATION WANTED ? TYPE Y FOR YES, N FOR NO
?N
CALCULATIONS FINISHED
Heat transferred (cooling required) D 1,590,000 kJ/100 kg
Note: though the program reports kJ/h, any consistent set of units can be used. For the
example the basis used was 100 kg.

Use of spreadsheets
A spreadsheet can be used for repetitive calculations as a simpler alternative to writing a
program. The procedure is set out below and illustrated in Example 13.14b.
From equation 13.11 the enthalpy of a stream, due to sensible heat, is given by
mDn T 2
2
3
4
H D m AT C BT /2 C CT /3 C DT /4 13.11a
mD1 T 1
where H D the stream sensible heat/enthalpy
m D flowrate of the steam component kg/s or kmol/s
n D number of stream components