Page 364 - APPLIED PROCESS DESIGN FOR CHEMICAL AND PETROCHEMICAL PLANTS, Volume 1, 3rd Edition

332 Applied Process Design for Chemical and Petrochemical Plants

Table 5-7 Table 5-8
Example Scale-Up of Two, D 2 /D 1, For Varying Order of Magnitude of Outside Film Coefficients, h
Mixing Slopes 16 Turbulent Range

Mixing Slope, x N2/N1 P2/P1 V2/V1 (P/V)2/(P/V)1 Helical Coils I Vertical Coils
Fluid BTU/(Hr.) (sq. ft.) (°F. between tank
0.5 ............... 1.0 32.0 8 4.0 fluid and coil fluid)
0.6 ............... 0.8 16.0 8 2.0
0.75 .............. 0.63 8.0 8 1.0 Water, 0.38 cp . 500-1100 500-1100
0.9 ............... 0.54 5.0 8 0.62 Oil, 10 cp . 20--70
I
1.0 ............... 0.50 4.0 8 0.50 Oil, 52 cp . 40-70 10-30
By permission; Rushton.]. H., Chem. Eng. Prog. V 47, (1951), pg. 485 [16].

4.Jackel [35][29]
For NRe > 4 X 10 in fluid bulk in tank
3
2 0.658 � 0.85( D'tp r [ ':µ J" [:. J" (; r
( ND p )
h (plate coil) (Ppcw /k) = 0.0317 - µ -
0
[ � )0.33 [..!:...)0.50 (5- 77) ( TD )0.13 (5- 78)
kw µf
Design Application
Some scale-up heat transfer relationships [29]:
A few typical overall heat transfer coefficients, U 0,
a) Laminar flow, R,, < 100 are presented in Table 5-9 [27] [29].
h., p HP (horsepower at the impeller shaft) Figure 5-41 indicates the mixing correlation expo-
b) For a constant impeller diameter, turbulent flow:
nent, x, as related to power per unit volume ratio for
ho p (HP) o.22 heal transfer scale-up. The exponent x is given in
c) For constant speed, same impeller type (family) Table 5-6 for the systems shown, and is the exponent
ho P (HP) o.29 of the Reynolds number term, or the slope of the

Table 5-9
Approximate Overall Heat Transfer Coefficients for Jacketed Mixing Vessels

U Expressed in BTU/hr/sq ft/°F
FLUID INSIDE FLUID IN
JACKET VESSEL WALL MATERIAL AGITATION u
Steam 'Nater Enameled C.l.* 0-400 R.P.M. 96-120 [25]
Steam Milk Enameled C.l. None 200
Steam Milk Enameled C.l. Stirring 300
Steam Milk boiling Enameled C.l. None 500
Steam Boiling water Steel None 187
Hot water \Va.rm water Enameled C.l. None 70
Cold water Cold water Enameled C.I. None 43
Steam Water Copper None 148
Steam Water Copper Simple 244
stirring
Steam Boiling water Copper None 250
Stearn Paraffin wax Copper None 27.4
Steam Paraffin wax Cast iron Scraper 107
,vater Paraffin wax Copper None 24.4
'Nater Paraffin wax Cast iron Scraper 72.3
"C.I. = Cast Iron
"*= or Glass-lined on steel
Adapted by permission: Lightnin/Unit of General Signal (27].