CEMP-E
TI 810-32
10 January 2002
APPENDIX D
CONDENSATION LOAD CALCULATIONS (STARTUP)
Step #1 Determine the heat loss per foot of line.
The startup load can be calculated by determining the amount of heat that is
required to heat the steam pipe from an ambient temperature to the saturation
temperature of the steam the pipe is to carry. This is done by using the
following equation:
= (vp * cp * ? p (tst - Tout))/t; Btu/ft
Q
where:
= ? (ro2- r2); in ft3/ft
vp
Step #2 Determine the pounds of condensate per foot from the heat loss calculated in step #1.
m
= Q/(hst - hcon); lbm/ft
Step #3 Multiply the condensate per foot, calculated in step #2, by the
total number of feet of steam line that slopes toward the drip leg in
question. Then convert the total pounds of condensate to gallons assuming
200 F condensate:
Total Condensate Volume (gallons)=(m*L)*7.49 gallons/ft3
60.1 lbm/ft3
where:
Q
= heat loss per foot of pipe; Btu/hr-ft
Tst
= temperature of steam; deg. F
Tout
= temperature of ambient conditions; deg. F
ro
= outside pipe radius; feet
ri
= inside pipe radius; feet
m
= mass flow rate of condensate; lbm/hr-ft
hst
= enthalpy of saturated steam; Btu/lbm
hcon
= enthalpy of condensate; Btu/lbm
cp
= specific heat of pipe (steel); (0.10 to 0.11) Btu/lbm/degrees F
? p
= density of pipe (steel); (489) lbm/ft3
t
= length of time for startup; hrs (typically 0.5 hrs.)
L
= total length of pipe draining to drip; ft
= volume of pipe material per foot; ft3/ft
vp
D-1
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