xchnager
TRANSCRIPT
Shell side fluid properties at mean temperature :
Cp = 2.47 Kj/kg C* 2470 J/kg C*
Density = 730 kg/m3
Visocsity = 0.43 mili Ns/m^2 0.00043 Ns/m^2
Thermal conductivity = 0.132 W/m C*
Tube side fluid properties at mean temperature :
Cp = 2.05 Kj/kg C* 2050 J/kg C*
Density = 820 kg/m3
Visocsity = 3.2 mili Ns/m^2 0.0032 Ns/m^2
Thermal conductivity = 0.134 W/m C*
Estimate Physical properties
Estimate Physical properties
Shell side fluid :
Mass flow rate of shell side fluid = 20000 kg/hr 5.555556 kg/sec
Inlet temperature of shell side fluid T1 = 200 C*
Outlet temperature of shell side fluidT2= 90 C*
Mean temperature of shell side fluid = 145 C*
Cp of shell side fluid = 2.47 kJ/kg C* 2470 J/kg C*
Tube side fluid :
Inlet temperature of tube side fluid t1= 40 C*
Outlet temperature of tube side fluid t2= 78 C*
Mean temperature of tube side fluid= 59 C*
Cp of tube side fluid = 2.05 Kj/kg C* 2050 J/kg C*
Q = m cp delT = 1509.4 Kw m = 5.555556 kg/sec
Cp = 2.47 kg/sec
T1= 200 C*
T2 = 90 C*
Mass flow rate of cold fluid , which is on tube side
m = Q/ Cp delT = 19.38 Kg/sec Q= 1509.444 Kw
69756.1 kg/hr Cp = 2.05 Kj/kg C*
t1 = 40 C*
t2 = 78 C*
What if cold fluid temperature is to be find out
Shell side fluid :
Mass flow rate of shell side fluid = 20000 kg/hr 5.555556 kg/sec
Inlet temperature of shell side fluid T1= 200 C*
Outlet temperature of shell side fluidT2= 90 C*
Mean temperature of shell side fluid = 145 C*
Cp of shell side fluid = 2.47 kJ/kg C* 2470 J/kg C*
Tube side fluid :
XxXchanger energy balance
Heat duty
XxXchanger energy balance
Inlet temperature of tube side fluid t1= 40 C*
Mass flow rate of tube side fluid = 70000 kg/hr 19.44444 kg/sec
cp estimation at inlet temp
Cp of tube side fluid at inlet tem= 2.05 Kj/kg C* 2050 J/kg C*
Q = m cp delT = 1509.444 Kw m = 5.555556 kg/sec
Cp = 2.47 kg/sec
T1= 200 C*
T2 = 90 C*
Outlet temperature of of cold fluid , which is on tube side
t2 = (Q/m cp ) + t1 = 77.87 C* Q= 1509.444 Kw
Cp = 2.05 Kj/kg C*
t1 = 40 C*
Heat duty
What if cold fluid temperature is to be find out
XxXchanger energy balance
XxXchanger energy balance
Mean temp at which cp will be estimated= 58.93
C*
For an Exchanger of this type the overall coefficeint will be found out from ,
see figure 12.1 and table 12.1 ;
U = 300 W/m2C*
Estimate Overall coefficeint Uo
Estimate Overall coefficeint Uo
An even number of tube passes is usually the preferred arrangement , as this position the inlet and outlet nozzles at the same end of the exchanger
which simplifies the pipe network
so strat with one shell pass and two tube passes
Inlet temperature of HOT fluid T1= 200 C*
Outlet temperature of HOT fluid T2 = 90 C*
Inlet temperature of Cold fluid t1= 40 C*
outlet temperature of Cold fluid t2 = 78 C*
LMTD = [ (T1-t2 ) - ( T2-t1) ]/ ln [ (T1-t2)/(T2-t1) ] 80.71767 T1 = 200
t2 = 78
T2= 90
t1= 40
R = (T1 - T2 )/ ( t2-t1)= 2.89 T1 = 200 C*
T2 = 90 C*
S = ( t2- t1) / ( T1-t1)= 0.24 t2= 78 C*
t1 = 40 C*
From figure 12.19 , P-657 , find here Ft factor using values of R and S
Ft = 0.88
so ,
Delta Tm = Ft * LMTD = 71 C*
Exchanger type and dimensions
An even number of tube passes is usually the preferred arrangement , as this position the inlet and outlet nozzles at the same end of the exchanger
C
C
C
C
Exchanger type and dimensions
Q= UA dELT
A = Q/U*dELT = 70.834 m2 Q = 1509444 W
U = 300 W/m2 C*
dEl Tm= 71 C*
Heat transfer area
Heat transfer area
Using split ring floating head exchanger for efficeincy and ease of cleaning.
Neither fluid is corrosive and the operating pressure is not high , so plain carbon steel can be used for the shell and tube.
Put the crude through the tubes and kerosene in shell
use tubes of ,
outside diameter 19.05 mm 0.01905 m
inside diameter = 14.83 mm 0.01483 m
Tube length = 5 m
tube pitch = 23.8125 mm 0.023813 m
Layout and tube size
Neither fluid is corrosive and the operating pressure is not high , so plain carbon steel can be used for the shell and tube.
Layout and tube size