Control of Volatile Organic Compounds Emissions from Manufacturing

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AREA OF A CONDENSATION SYSTEM OF STYRENE IN AIR (Conti nued)
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I Dfrty overall heat trans er
coefficient (Ud), Btu/ft d-hr-OF [(I t Uc) + 0:00l]~l
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Log mean temperature di fference (LMTD) , OF [AT1 - LIT2) + In (AT~/AT~)
Requlred heat transfer area (A), ft2
Total tube length required (Lt), ftj I
Required heat exchanger length (LHaE. ), ftK Lt s 17
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9p0k +, (UD x LMTD);
> 43.8 ft2, try
heat exchanger'
Required refrigeration capacity (RC') , tons1 Qtot + 12,000
Selected refri geration capaci ty (RC) , tons RC' or minimum of 1
Wondenser and tube characteristics from pp. 11-1 thru 11-18 of the
Chemical Engineers ' Handbook (Reference 30) :
Tube: outer diameter, Do = 1.00 in.; inner diameter, Di := 0.870 in. ;
thickness Xw = 0.065 in.; specific external surface area =
0.2618 ft?/ft;
cross-sectional area = 0 .OO4l28 ft2/tube
, ,
Condenser: shell inside area, Ai = 0.3553 f$*;
total tube area, A = 0.09272 ft ;
net area = 0.2626 b.2, wetted perimeter = 6.54 ft;
hydraulic radius, rH = 0.04001 ft.?
length, L = 8 ft, total cross-sectional area inside of
tubes = 0.004128 ft2/tube x 17 tubes = 0.07018 ft2.
, , , ,, ,,,
b~ssuming baffle cuts, 1, = 0.25 (shell diameter, DS); shell outer tube
limit, D ti x7.634 in. (7/16" clearance for fixed tube sheet for
DS -< 241'7; baffle spacing, bS = DS s 8 in.
CCoolant characteristics can be interpolated or extrapolated for the
coolant temperature, Tc, from The Chemical Engineers ' Handbook:
pp, 3-71, 206, 213, & 214 (Refeece 34) for water; pp. 12-46 thru 12-48
(Reference 31) for ethylene glycol water solutions; and pp. 3-191 and
3-212 thru 3-214 (Reference 31, plus p. E-26 (Reference 32) of The Hand-
book of Chemistry and Physics for Freon-12 (di chlorodi fluoromethane).
Characteristics requi red are dynamic viscosity ( p ) , der1sit.y (p),
specific heat (c ), thermal conductivity (k), and specific gravity (y)
= P/62,42, 1b/ft 9.
d~orcoolant velocity, V = 3 fps (3-10 fps recommended by Kern in Process
Heat Transfer (Reference 35).
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