Transactions

548 TRANSACTIONS OF TH E A.S.M.E. AUGUST, 1941
T A B L E 1 R U N S O N B O IL IN G BEN ZEN E®
(Steam used in all twelve jackets in all runs)**
Start of
boiling
section,
Start of
superheating
section,
W eight
Feed Feed Steam
H eatc Inlet Outlet per cent
Pressure
R un rate, temp, pressure, transfer, velocity, velocity, of feed per cent per cent drop,
no. lb per hr C psi gage B tu per hr fps fps vaporized of jacket of jacket cm Hg
B-6 1010 54.5 114.0 136000 0.94 175 66 20 of J 2 20.1
B-3 990 52.5 108.0 161000 0.92 220 82 10 of J 2 24.4
B-2 906 45.0 12.7 183000 0.84 240 100 10 of J 2 50 of J 12 37.4
B-4 1080 55.8 1.9 149000 1.00 185 66 90 of J 3 20.8
B-7A 1030 58.5 2.1 146000 0.95 190 73 70 of J 3
B - ll 818 50.5 64.0 141000 0.76 190 87 60 of J 1 23.0
B-10 689 44.5 34.0 152000 0.64 200 100 50 of J 1 60 of J 9 26.7
B-9 710 45.0 28.0 157000 0.66 210 100 50 of J 1 10 of J 8 32.0
B-8 750 45.7 13.4 157000 0.69 205 100 E nd of J 1 50 of J 10 33.2
B-l 615 42.5 1.5 125000 0.57 170 100 40 of J 2 50 of J 12 20.2
B-5 650 47.0 1.5 122000 0.60 165 96 95 of J 2 17.4
B-7 700 45.5 1.2 127000 0.65 170 91 10 of J 3 17.4
B-14 713 44.0 1.1 124000 0.66 160 85 60 of J 3 18.0
B-1A 704 47.5 1.6 129000 0.65 165 91 10 of J 3 20.9
B-4A 674 51.5 1.7 127000 0.62 180 100 80 of J 2 90 of J 12 19.6
B-6A 720 48.0 2.1 131000 0.67 175 92 E nd of J 2 19.1
B-12 448 45.5 74.0 87000 0.42 120 98 70 of J 1 9.3
B-2A 434 41.0 1.6 91000 0.40 120 100 20 of J 2 40 of J 9 11.7
B-5A 453 46.0 1.8 92000 0.42 130 100 30 of J 2 70 of J 9 12.3
B-13 289 37.5 70.0 60000 0.27 80 100 70 of J 1 70 of J 12 4.6
B-3A 282 36.0 1.8 60000 0.26 81 100 80 of J 1 10 of J 6 5.7
° Refer to Bibliography (6).
b Inside heated area of copper pipe = 0.88 sq ft per jacket.
c Based on steam-condensate measurements.
rate, the highest coefficients being obtained at the intermediate
feed rate. This difficulty is overcome in Fig. 6, where, at the
lower velocities the coefficients are independent of the feed rate
and, at the higher velocities, higher coefficients are consistently
F i g . 6
R e s u l t s o f F i g . 5 R e p l o t t e d a s U V e r s u s A v e r a g e
V e l o c i t y
F i g . 5
P - CUMULATIVE WEIGHT PER CENT VAPOR
P l o t o f L o c a l O v e r - A l l H e a t - T r a n s f e r C o e f f i c i e n t
V e r s u s C u m u l a t i v e W e i g h t P e r C e n t V a p o r f o r A l l B e n z e n e
R u n s a t L o w S t e a m P r e s s u r e ; 1 .2 t o 2 .1 Psi G a g e
(M a x im u m lo c a l co efficien ts are o b ta in e d a t c r itic a l v a lu e s of p, b u t siz e of
m a x im u m coefficien t a n d c r itic a l p are a ffe cte d b y fe e d r a te .)
cent vaporization, depended upon the feed rate, being 940 and 45
per cent, 700 and 55 per cent, and 540 and 60 per cent when the
feed rates were 1050, 680, and 390 lb per hr, respectively. The
first run taken in the apparatus (run No. B-l, shown by triangles
in Fig. 5) yielded abnormally high coefficients which could not be
duplicated in subsequent runs. In Fig. 5, arrows are used to
designate data taken from jackets Nos. 4, 7, and 10 (immediately
following a return bend) when the cumulative per cent vapor was
greater than 60 per cent.
Fig. 6 shows the coefficients of Fig. 5 plotted against the average
linear velocity, arbitrarily taken as the geometric mean of the
calculated velocities entering and leaving that section, deleting
the data shown by triangles and arrows in Fig. 5, and adding data
for sections where vaporization started. If the curves of Fig. 5
are compared, it will be found that, in the range of p from 55 to
70 per cent, the coefficients are complicated functions of the feed
F i g . 7 E f f e c t o f S t e a m P r e s s u r e a n d P e r C e n t V a p o r i z e d f o r
B e n z e n e R u n s W i t h F e e d R a t e s R a n g i n g F r o m 6 1 5 t o 8 1 8 L b
p e r H r ; C u r v e s f o r P o f 1 .6 F r o m F i g . 5