Performance of Two 101,000-Sq

FSP-56-3
P erfo rm an ce of T w o 101,000-Sq-Ft S urface
C o n d en sers
By J. N. L A N D IS 1 a n d S. A. T U C K ER ,2 B R O O K LYN , N . Y.
The results o f tests o f tw o 101,000-sq-ft single-pass c o n ­
densers in th e H u d s o n Avenue S ta tio n o f th e B ro o k ly n
Edison C o m p a n y are s u m m a r iz e d , a n d th e design features
are briefly described. T he steam-flow p a t h o f th e W o r t h ­
in g to n condenser is th r o u g h a n effectively shallow tu b e
b a n k o f th e folded-layer type, h a v in g deep in le t lanes to
facilitate th e passage o f ste a m w ith m i n i m u m pressure
drop. The e n tire tu b e b a n k is c o n ta in e d in a p ra c tic a lly
cylind rical shell. I n th e Ing erso ll- R an d u n it th e generally
heart-shaped shell m a in t a in s w ith a decreasing v o lu m e o f
steam a n active flow over a ll tube s. Bypass lanes a r o u n d
th e to p sections o f tube s allow p a rt o f th e ste a m to reach
th e low er tu b e b a n k s w it h o u t p assin g t h r o u g h th e to p
section. T he W o r th in g to n a ir cooler is placed in te r n a l
to th e shell as b e in g th e m o s t c o n v e n ie n t lo c a tio n a n d i n ­
volving th e least costly c o n s tr u c tio n . T he IngersollR a n d de sig n uses a n ex te rn al a ir cooler to provide a m ore
effic ien t de sig n o f flow areas. R e h e a tin g is provided for in
th e co nd en sate c irc u its o f b o th u n its , th e W o r th in g to n
u s in g a co nta ct- ty pe r e h e a tin g h o tw e ll in te g r a l w ith th e
condenser a n d th e In g e rso ll- R a n d h a v in g a 1600-sq-ft-surface closed rehe ate r a fte r th e co nd e n sate p u m p , su pplie d
w ith ste a m fr o m one o f th e to p bypass belts. Steam -flow
co n tro l, a ir rem o val, a n d c ir c u la tin g system s are c o m p a r e d .
H IS paper presents a brief summary
of the results of tests of two 101,000sq-ft single-pass condensers in the
Hudson Avenue Station of the Brooklyn
Edison Company.
units, the W orthington using a contacttype reheating hotwell integral with the
condenser and the Ingersoll-Rand having
a 1600-sq-ft-surface closed reheater after
the condensate pump, supplied w ith steam
from one of the top bypass belts.
In the W orthington unit, a free longi­
tudinal flow of steam is permitted by open­
ings cut in the six tube support sheets
wherever possible. Quite in contrast, the
Ingersoll-Rand unit, as shown in Fig. 2,
is divided into five separate longitudinal
S. A. T u c k e r
compartments by four closely fitted tubesupported sheets.
Each of the three
cold-end compartments is separately connected to its own sec­
tion of the external air cooler, and the two warm-end compart­
ments are connected in parallel to the remaining section of the
air cooler with a throttle plate to lim it the flow from the end
compartment. Air removal is accomplished on the W orthing­
ton unit by a three-element two-stage steam jet, and on the
Ingersoll-Rand unit by eight primary and three secondary jets.
Each condenser is served by two circulators, with separate
water circuits from the inlet to the discharge tunnels. The
Worthington unit, as shown in Fig. 3, has a conventional verti­
cally divided water box, whereas the Ingersoll-Rand water box
is divided into four horizontal sections, arranged for each cir­
culator to supply two alternate sections. There are no valves
in the m ain circulating-water system of either condenser.
T
D
e s ig n
C
o m p a r is o n s
Since these two condensers have been
extensively described elsewhere,3 only a
brief statement of their design features is
given here.
The steam-flow path of the W orthing­
ton condenser, shown in Fig. 1, is through
J- N. L a n d i s
an effectively shallow tube bank of the
folded layer type, having deep inlet lanes to facilitate the pas­
sage of steam with m inimum pressure drop. The entire tube bank
is contained in a practically cylindrical shell. In the IngersollR and unit, the generally heart-shaped shell maintains with a
decreasing volume of steam an active flow over all tubes. B y­
pass lanes around the top sections of tubes allow part of the
steam to reach the lower tube banks without passing through the
top section.
The Worthington air cooler is placed internal to the shell as
being the most convenient location and involving the least costly
construction. The Ingersoll-Rand design uses an external
air cooler to provide a more efficient design of flow areas.
Reheating is provided for in the condensate circuits of both
1 Mechanical Engineer, Brooklyn Edison Company, Inc. AssocMem. A .S.M .E . Mr. Landis received the degree of B.S. in Mechani­
cal Engineering in 1922 from the University of Michigan. He went
with the Brooklyn Edison Company in 1923 as technical assistant
to the mechanical engineer, and since th at time has been intimately
associated in various capacities w ith the design and construction of
the Hudson Avenue Generating Station. He was appointed to his
present position in 1932.
2 Division Engineer, Plant Equipm ent Bureau, Brooklyn Edison
Company, Inc. Mr. Tucker received his B.S. in Electrical E n ­
gineering in 1926 from Yale University. He was employed by the
Brooklyn Edison Company, Inc., in 1926 as a cadet engineer, and
since 1928 he has been a member of the Plant Equipm ent Bureau.
s Power Plant Engineering, April 15, 1932, November, 1932; Power,
May 31, 1932.
Presented at the Semi-Annual Meeting, Chicago, 111., June 26 to
July 1, 1933, of T h e A m e r i c a n S o c ie t y o f M e c h a n i c a l E n g i n e e r s .
N o t e : Statements and opinions advanced i n papers are to be
understood as individual expressions of their authors, and not those
of the Society.
A
cceptance
T
ests
The tests on these two condensers represent the culmination
of several years’ experience in performing tests on large powerplant equipment, including several condensers, by a group of
test men organized principally for acceptance testing. The
results are presented w ith the belief th at they summarize the
most comprehensive and carefully executed condenser tests
publicly reported.
The tests were unusual in that they determined the “ cleanli­
ness ratio” of the condensing surface. The manner of making
the cleanliness ratio measurements has already been discussed in
detail before the A .S .M .E . by Messrs. Hardie and Cooper.4
* “A Test M ethod for Determining the Quantitative Effect of Tube
Fouling on Condenser Performance,” by P. H . Hardie and W . S.
Cooper. Trans. A .S .M .E ., vol. 55 (1933), paper RP-55-3
167
168
TRANSACTIONS OF THE A M ERICA N SOCIETY OF MECHANICAL EN GINEERS
In brief, the test consisted of determining the individual per­
formance of 30 isolated tubes in various parts of the condensers,
arranged in six groups of five tubes each, supplied with inde­
pendently controlled circulating water. Each group of five tubes
consisted of two new tubes and three existing used tubes repre­
sentative of the condition of the condensing surface at the time
of test. One new tube in each group was supplied with salt
water, and the other, for purposes of a separate investigation,
with fresh water. The ratio of the average thermal transmit­
tance of the used tubes to the average transmittance of the salt­
water new tubes was taken as the “ cleanliness ratio” of the con­
denser. In their contracts these condenser manufacturers and
all others made guarantees which were to be corrected downward
from a 100 per cent clean transmittance guarantee in direct pro­
portion to the cleanliness ratio obtaining at time of test.
number of basket-type pressure tips distributed over
the area of the turbine exhaust
4 Absolute pressure at (each compartment of) the hotwell
by absolute-pressure gages identical with those used at
the turbine exhaust
5 Condensate temperature leaving the hotwell (and the
reheater) by precision mercurial thermometers.
The amount of steam condensed was determined by weighing
the condensate in the station weighing tanks. Sufficient read­
ings were taken of turbine-throttle and feedheating conditions to
permit computing the heat content of the exhaust steam.
To ascertain the condenser-cleanliness factor during the period
of test, six groups of isolated tubes were connected by a rubber
hose to a separate supply of salt water measured at the outlet
end by a calibrated bell-mouthed nozzle. One new tube in each
F ig . 1
Each of the two acceptance tests consisted of nine 1-hr runs,
confined to a period of two days. These runs covered the normal
operating range of the turbine for both high and low speeds of
the circulating pumps. During the night preceding the start of
test runs, each condenser was completely rubber-plugged to
secure uniformity of tube condition, and thus the most repre­
sentative cleanliness ratio as measured from the relatively few
sampling tubes.
A c c e p t a n c e -T e s t P r o c e d u r e
and
A
pparatus
Readings were taken at 5-min intervals of—•
1
2
3
Inlet circulating-water temperature by two precision
mercurial thermometers graduated to 0.1 deg F
Outlet circulating-water temperatures by six precision
mercurial thermometers graduated to 0.1 deg F
Absolute pressure at the steam inlet by 11 specially con­
structed absolute-pressure gages connected to an equal
group was supplied with fresh water as a reference standard to
indicate any tendency of the salt-water new tube to foul. The
flow of water in each tube was held approximately the same as the
average of all the condenser tubes. For measuring the tempera­
ture rise in each tube, mercurial thermometers were inserted
through rubber stoppers directly into the water stream.
Air offtake temperatures were measured by mercurial ther­
mometers inserted through rubber stoppers, and air leakage was
determined from the standard equipment furnished by each
manufacturer as part of the contract.
Pressure drops for each part of the circulating-water system
and the total and suction heads on the pumps were determined by
mercury U-tubes. The electrical input and speed of the circula­
tor motors were also separately measured. The principal test
data are given in Table 1.
Fig. 4 shows for the Worthington unit the absolute pressure
and the calculated heat-transmittance coefficients obtained for
FUELS A N D STEAM PO W ER
both high- and low-speed pum p operation. Fig. 5 is a plot of
the same results obtained on the Ingersoll-Rand unit.
A question may arise as to why the curves of both tests show
different cleanliness ratios at low and high speed on the circula­
tors. Fig. 6 shows the results of calorimeter measurements per-
FSP-56-3
169
170
TRANSACTIONS OF THE A M ERICA N SOCIETY OF MECHANICAL ENGINEERS
TABLE
1
ACTUAL
CONDENSER
Run
No.
Date,
1932
Abs.
H eat
pressure
transf.
at
H otwell Circ-water temp.
Steam
by cond., condenser tem p.,1 O u t,
In ,
condensed,
m illion
nozzle,
deg
deg
deg
per hr
B tu per hr in. H g
F
F
F
1
5
6
9
10
6-13
6-13
6-14
6-14
6-14
732,100
562,900
995,800
1,389,700
731,300
684.0
531.4
923.4
1282.1
682.1
1.09
0.93
1.36
1.82
1.09
81.7
76.5
88.5
97.7
81.7
2
3
4
7
8
11
6-13
6-13
6-13
6-14
6-14
6-14
721,600
432,600
568,700
992,600
1,395,500
735,900
675.3
416.4
536.4
920.9
1286.2
684.5
1.20
0.89
1.01
1.57
2.13
1.21
84.2
75.6
79.5
92.8
102.9
84.9
5
6
9
10
6-27
6-28
6-28
6-28
643,000
1,008,100
1,350,300
768,600
601.7
932.3
1249.5
714.1
1.10
1.46
1.80
1.22
82.1
90.7
97.0
85.3
3
4
7
8
11
6-27
6-27
6-28
6-28
6-28
487,200
643,100
1,012,000
1,361,000
772,500
463.2
602.1
935.3
1256.9
717.6
1.08
1.24
1.75
2.26
1.40
81.3
85.8
96.5
105.2
89.9
PERFORM ANCE
Heat
transHeat
mittrans­
tance1
mittance,
Av.B tu,
B tu per
temp, per hr
,—Condenser—•. hr per sq ft
Air
air per sq ft
friction
per deg Clean- re­
off- per deg
A
B
F log
liness moved,, take, F log
°F m .t.d.
ft2
f t2
m .t.d. factor c.f.m.
Circwater
flow,
gpm
W orthington Condenser , H igh Speed
71.6
63.3
167,800
..«
68.1
61.6
165,400
..3
7 4.0
62.7
166,500
17.3
77 .5
61.9
167,800
17.9
69.9
61.4
163,800
17.9
17.3
17.7
17.6
17.7
17.9
490
455
463
459
432
0.68
0.68
0.61
0.59
0.59
9.-5
9 .5
9.7
9.7
9.6
9.9
449
421
425
422
428
399
14.7
15.2
15.4
15.3
6.8
6.8
6.8
6 .8
6.8
. .4
Abs.
pres­
sure®
at
con­
denser
nozzle,
in. Hg
4
5
5
6
76
73
82
90
79
459
437
489
507
483
1.08
0.95
1.29
1.70
1.05
0.72
0.72
0.71
0.64
0.62
0.60
4
5
4
5
5
6
79
72
76
87
96
81
419
400
408
442
472
453
1.19
0.91
1.04
1.49
2.01
1.16
553
563
576
551
0.78
0.75
0.74
0.74
4
4
2
2
78
85
91
81
542
575
596
575
1.13
1.42
1.76
1.21
493
493
501
513
496
0.82
0.81
0.77
0.76
0.76
4
4
2
2
2
80
83
92
99
86
479
480
513
531
517
1.11
1.27
1.69
2.20
1.38
W orthington Condenser , Loxo Speed
74.1
6 8.9
7 1.0
78.4
83.1
73.1
62.7
61.7
61.9
62.9
61.6
61.5
120,500
118,300
119,500
121,200
121,900
119,800
. .3
..3
9.6
9 .7
9 .9
Ingersoll-Rand Condenser, H igh Speed
74.3
79.4
82.7
75.9
67.3
68.5
68.2
67.6
176,400
175,300
176,300
175,100
15.6
14.5
14.3
14.3
Ingersoll-Rand Condenser, Low Speed
75 .5
78.1
85.4
90 .5
80.7
67.3
67.4
68.6
68.1
68.0
115,500
115,300
113,600
114,500
114,900
7.1
7 .0
7 .0
6 .8
6.8
1 For Ingersoll-Rand temperature at reheater outlet. 2 Feet of salt water. * Gage inoperative. 4 Air leak found after first half-hour. * W orthington
corrected to: H igh speed, 166,000 gpm ; 0.65 cleanliness factor; 62 F inlet temperature. Low speed, 120,000 gpm ; 0.68 cleanliness factor; 62 F inlet
temperature. Ingersoll-Rand corrected to: H igh speed, 176,000 gpm ; 0.765 cleanliness factor; 68 F inlet temperature. Low speed, 115,000 gpm ; 0.79
cleanliness factor; 68 F inlet temperature.
formed by the Ingersoll-Rand Company in 1929 on several
used tubes taken from a Hudson Avenue condenser and on two
sections of new tube. This test work illustrates that dirty
tubes do not respond to increases of velocity as do clean tubes.
This condition is explained by the fact that an increase of water
velocity effects a reduction only in the resistance to heat flow
of the water film, which is a much smaller proportion of the
total resistance in the case of a dirty tube than in the case of a
clean tube.
C
o n c l u s io n
I t is natural to expect this paper to make a final comparison
of the performance of the two condensers. In order to do this it
would be necessary to make corrections to the test results be­
cause of the unavoidable differences in test conditions relating to
cleanUness, circulating-water quantity, and circulating-water
temperature. The manufacturers’ correction for cleanliness
has been discussed, and the correction factors commonly used
by condenser manufacturers for the effect of circulating-water
velocity and temperature are available in the technical press.6
The authors might use these correction factors as a basis for a
final comparison of the two condensers, but because they are of
the nature of values accepted by the manufacturers for commer­
cial purposes instead of being values derived from test from the
specific condensers in question, it is considered better to confine
this paper to the reporting of test facts and to leave to others the
making of comparisons.
The test results are believed to show fairly the performance of
two modern condensing units under as closely parallel conditions
as it is practical to secure.
Both condensers have performed satisfactorily, and in their
ability to hold materially better than the guaranteed full-Ioad
vacuum they have exceeded expectations by a comfortable
margin.
under the direction of Mr. P. H. Hardie, Test Engineer of the
Brooklyn Edison Company’s Research Bureau.
Discussion
P a u l B a n c e l .6
The paper is an important contribution to
the literature on surface condensers. A great deal of thought,
time, and money lies behind the testing work of the Brooklyn
Edison Company. The difficulties incident to testing a con­
densing plant of this great capacity can hardly be realized.
The design of the Ingersoll-Rand condenser follows the funda­
mental principles of all condensers built by the company, but
in view of the special problems associated with the size of this
unit, two sets of experiments employing models were made pre­
liminary to construction.
A cknow ledgm ent
The acceptance tests on both condensing units were performed
‘ “Commercial Factors
Power, September, 1932.
for
Designing
Surface
Condensers,”
F ig . 7
T y p ic a l M
odel
W
a t e r -B o x
6 Manager, Condenser Department,
New York, N. Y . Jun. A.S.M.E.
T est
Ingersoll-Rand
Company,
FUELS AN D STEAM PO W ER
FSP-56-3
171
Tests were made to study the flow lines
and areas in the water boxes, 28 model
set-ups being photographed. The actual
boxes were to be divided into four hori­
zontal compartments, with side admis­
sion, and the model tests were made to
determine the best flow paths for m ini­
mum turbulence when feeding the water
from twin nozzles located at the bottom
of the inlet box and discharging from two
nozzles on opposite sides near the top of
the outlet box.
Photographs shown in
Figs. 7 and 8 are typical. The model is
a composite arrangement for both inlet
and discharge to the first and third com­
partments served by these water nozzles.
Side admission to a water box divided
into horizontal compartments at differ­
ent heights improves the flow conditions
at the entrance to the tubes, thus elimi­
nating troubles from inlet-tube corro­
sion. The frothing effect of the water
is greatly reduced because of the shallow­
ness of each compartment and the rela­
tively small difference in water pressure
between the top and the bottom; further­
more, the horizontal flow tends to pre­
vent pocketing and regions of air libera­
tion and frothing. At the East River
Station of the New York Edison Com­
pany, this design, combined with vent­
ing, in a water box divided into three
horizontal compartments, has eliminated
inlet-tube corrosion.
The second series of tests were more
elaborate. Figs. 9A to 9E show model
condensers which were built to study
comparative pressure losses of different
tube layouts. In each case the number of
F i g . 9 M o d e l C o n d e n s e r -T o b e S h e e t s a s U s e d f o b C o m p a e a t i v e P r e s s u r e - D r o p T e s t s
tubes per square foot of tube-sheet area
is the same. Relatively large quantities
of steam at high vacuum were passed through these small confor accurate measurement. In this way characteristic curves
densers, part of the steam being condensed and the remainder
were obtained of the pressure loss with varying flows through
being rejected to a supplementary condenser. The total steam
the different tube banks.
On the basis of these tests, the tube
flow was several thousand pounds, so that the steam condensed,
arrangement for the actual condenser was selected and the pressteam rejected, velocities, pressure drops, etc. were amply large
sure drops calculated.
The actual pressure drops for the five longitudinal compart­
ments during test 11 are given in Fig. 10 based on observations
taken by the Brooklyn Edison Com pany’s Research Bureau. The
table gives the calculated loading per square foot in each com­
partment when the entire surface is satisfied. The relatively
cold water in the first compartment results in a condensing
capacity over twice that of the last compartment. The agree­
ment of the measured drops with the calculated gradations is very
close.
The average pressure loss is 0.104 in., as shown. On the warm
end it is so small that it was difficult to measure. The pressure
loss at the cold end is about 0.2 in., and this is evidence that the
steam flow in this section was in accordance with the calculated
condensing capacity.
The paper m ay give the impression that there is insufficient
area between the turbine and the entrance to the tube bank of
the Ingersoll-Rand condenser for easy or free deflection of flow
toward the cold end. Figs. 10 and 11 and the following calcula­
tions show that any force to cause deflection of the steam be­
F i g . 8 T y p ic a t , M o d e l W a t e r -B o x T e s t
tween the time it leaves the turbine and enters the tube bank is
172
TRANSACTIONS OF THE A M ERICA N SOCIETY OF MECHANICAL ENGIN EERS
negligible. The writer appreciates that steam flows and pressure
are far from uniform in a turbine-exhaust casing, but this does
not alter the present line of reasoning.
As shown, one-half of the steam is condensed by the first two
compartments; the center of flow of this half of the steam is
shifted about 2 ft toward the cold end. Therefore, the hori­
zontal component of the velocity diagram is 2 ft as against
20 to 10 ft vertical component, depending on whether the stream
starts to bend near the top or near the bottom of the turbine
casing. The horizontal component is therefore 10 to 20 per cent
of the vertical. The average flow velocity is about 250 ft per
sec at the turbine nozzle and considerably less (150 to 200 ft)
at the condenser. I t follows that the horizontal component
may be as low as 15 to 25 ft per sec and not over 50 ft per sec.
In other words, the required velocities and forces of deflection
are exceedingly small. In contrast the forces required for pene­
tration at one end as compared to the other are appreciable and
can be readily measured in terms of pressure drop. I t should be
emphasized that the problems of steam deflection are entirely
distinct and different from those of steam penetration.
C. F. H a r w o o d . 7 The method developed for determining
the relative percentage of tube cleanliness in a surface condenser
discloses the skill and accuracy displayed in obtaining the data
reported in this paper. The performance of both condensers as
F i g . 10
D
ata
F h o m A c c e p t a n c e -T e s t R
R and C ondenser
un op
I ng ersoll-
F i g . 12
C o r r e c t io n s
of
C u r v e s Sh o w n
in
F iq . 5
of
P aper
indicated by these tests is of a high order, especially so in view
of the percentage of tube fouling present.
I t is unfortunate that the tests on both units were not made
under more nearly equal conditions of tube cleanliness and circulating-water temperature, so that a comparison of performance
could be made without the necessity of applying any corrections
for the differences in water temperature, quantity, and tube
F ig .
11
L o n g it u d in a l St e a m D is t r ib u t io n ,
C o nden ser
I n g e r s o l l -R a n d
7 Manager of Steam Power Plant Sales, Worthington Pum p and
Machinery Corp., Harrison, N. J.
FUELS AND STEAM POWER
FSP-56-3
173
cleanliness obtaining when the observations were taken, but
unless such corrective factors are applied it is difficult to obtain a
correct idea of the relative performance of the two condensers.
A casual inspection of the data and curves indicates that the
Worthington condenser is producing a lower absolute pressure
with a lower temperature of circulating water and with dirtier
tubes, and that the Ingersoll-Rand condenser is showing a higher
coefficient of heat transfer with a higher temperature of circulat­
ing water and cleaner tubes, but the extent to which these
differences in water temperature and tube cleanliness would
affect comparative performances can only be made evident by
the application of correction factors which will place both units
on a common basis of tube cleanliness, circulating-water tem­
perature, and quantity. The authors state that the application
of such corrections has been left to others, and there are therefore
submitted herewith curves for both condensers showing absolute
pressures and coefficients of heat transfer based upon equal
conditions of circulating-water temperature and quantity, and
equal percentages of tube cleanliness.
These curves have been constructed in the following manner:
The performance curves of the Ingersoll-Rand condenser, drawn
in dotted lines, have been reproduced in Fig. 12 as shown by the
authors in Fig. 5 of their paper. The performance curves of
the Worthington condenser, shown in full lines, have been
plotted from the “ actual condenser test performance” data con­
tained in the paper, with the necessary corrections applied to the
observed circulating-water temperatures and quantities and
percentage of tube cleanliness, so that these correspond to
those of the Ingersoll condenser as indicated in Fig. 5 of the
paper.
These corrections are made on the following bases: (a) Circulating-Water Temperature. By means of the temperature
correction curve incorporated in the September, 1932, issue of
Power and which is in common use by practically all condenser
manufacturers today. (6) Circulating Water Velocity. In
accord with ratio of square roots of velocities, (c) Tube Cleanli­
ness. In ratio of observed percentages of cleanliness, as such
cleanlinesses are stated in the paper.
Both condensers are therefore placed on a common basis of
operating conditions, and their relative performance is more
clearly indicated.
8.3 fps at high-speed operation and 5.93 fps at slow-speed for
the Worthington condenser, and 8.88 fps at high-speed operation
and 5.8 fps at low-speed for the Ingersoll-Rand condenser.
The tube-fouling conditions at this station may warrant and
justify the high velocities used, as high velocity is conducive to
maintenance of clean tubes under certain conditions of fouling.
The authors mention the fact that the two condensers de­
scribed are radically different in design. This leads one to
suggest that No. 6 unit, operating in the same station, should
have been included in the comparison. Naturally, in expressing
this thought the writer has a selfish motive in mind.
The performance of No. 6 unit was creditable, and when
equated to the same basis indicates performance comparable
with the condensers described by the authors. This condenser
gave a Btu rate of 410 at high-speed operation, corresponding to
7.0 fps water velocity. Compared on the same basis as the
Worthington and the Ingersoll-Rand, the rate becomes 594 to 630
Btu, depending upon whether a cleanliness factor of 65 per cent
or 69 per cent is used.
Equating the velocities to a common basis would justify a
rate of 780 Btu for No. 6 unit, at the equivalent velocity.
Results indicating the performance with larger quantities of
air leakage would be of interest, because experience indicates
that condenser performance is appreciably affected by increased
leakage.
The writer has noted a reduction in the transfer rate of approxi­
mately 35 per cent on isolated tubes located in the so-called
active part of the tube nest, merely by increasing the air leakage,
all other conditions remaining the same. He mentions this
fact because of its importance in comparing test results. It
should be noted that in the case of the Ingersoll-Rand the leakage
varies from a minimum of 2 to a maximum of 4 cu ft per min.
The Worthington varies from 4 to 6 cu ft per min. The air
leakage on the No. 6 unit varied from 4 to 16 cu ft per min.
The authors mention the fact that tests illustrate that dirty
tubes do not respond to increased water velocity. This state­
ment is verified by tests made under the writer’s direction, and
covering the period from 1917 to 1926. The slope of the curve
with clean tubes closely approximates the established law,
varying as 0.5 power, whereas, depending upon the nature of
fouling, a dirty tube varies as 0.2 to 0.3 power.
Referring to Fig. 6, the writer would like to know if tests were
D.
W. R. M o r g a n . 8 The main value of the paper is that it made condensing or non-condensing.
demonstrates the feasibility of equating actual performance
The authors suggest the great need of advancing the knowledge
with guarantees, and if properly applied, eliminates the argu­
of the subject of condensers, comparable to that of turbines.
ment between manufacturer and operator concerning the condi­
The writer thoroughly agrees with the conclusion. However,
tion of the tube surface at the time of tests. Further, the data
he wishes to point out that difficulties lie before us, and a greater
may be used by the operator in determining what factor to apply
amount of standardization must be accepted by the operator
as regards excess surface and water, in order to maintain the
on such vital points as: (1) Relation of condenser to turbine
desired vacuum under average operating conditions.
exhaust—namely, set at right angles or parallel to the turbine
The authors state that both condensers have performed satis­ shaft. (2) More thorough exploration of pressure at inlet of
factorily and maintain better than guaranteed full-load vacuum.
condenser and through the tube nest. (3) A uniform distribu­
Emphasis should be laid on the fact that this good performance
tion of steam from the turbine exhaust.
is not evident if one simply accepts from casual examination the
actual Btu transfer rates referred to in the paper. As an ex­
J o h n F. G r a c e . 8 Were both condensers tested under more
ample, the maximum rate of the Worthington condenser is 507 uniform cleanliness and water temperature and were they the
Btu; the maximum rate for the Ingersoll-Rand is 596 Btu.
product of one maker, discussion of factors of correction would
Equating these values to the nominal guarantee basis, they
not be so wide or so susceptible to the sales viewpoint, against
become, respectively, 780 Btu for both condensers, assuming the
which engineers have developed no satisfactory screening equip­
average cleanliness specified.
ment.
However, it should be noted that although the Btu rates are
The layout engineer senses that performance is influenced by
good, they were obtained at the expense of high velocity, and
simplicity of arrangement and connections. The builder of the
therefore increasing the pumping cost. Based on information
heart-shaped condenser required a wider turbine supporting
published in Power, the water velocities through the tubes are
structure and more liberal space than the builder of the cylindrical
* Westinghouse Elec. & Mfg. Co., South Philadelphia, Pa. Assoc* Condenser Engineer, Worthington Pump and Machinery Corpo­
Mem. A.S.M.E.
ration, Harrison, N. J., Mem. A.S.M .E.
174
TRANSACTIONS OF THE A M ERICA N SOCIETY OF MECHANICAL EN GINEERS
condenser, who would have further improved performance if
granted equal space. Figs. 1, 2, and 3 show both condensers to
the same scale, and Fig. 1 shows the cylindrical condenser pre­
senting the longer line of “front row” tubes.
The layout of the 160,000-kw units at Brooklyn is with con­
denser tubes parallel to turbine shafts and both 90 deg to crane
rails. Lateral space is thus important to accessibility, operation,
and performance. Seven such units can be comfortably housed
in a turbine room of the dimensions at Hudson Avenue if heartshaped condensers are installed, while eight can be as well housed
if the cylindrical type is chosen. Space is thus a serious “per­
formance” factor, and the cost of a building to house an addi­
tional 160,000-kw turbo-generator and auxiliaries is a not in­
considerable item when limits of output and of downtown real
estate are approached.
TABLE 2
W E IG H T E D A V E R A G E AS R E C O M M E N D E D B Y
M R . H O D G K IN S O N
U
U
Test No.
as reported
W - l.......................................................
0.68
W-5.......................................................
0.68
W-6.......................................................
0.61
W-9.......................................................
0.59
W-10.....................................................
0.59
IR - 5......................................................
0.78
IR - 6......................................................
0.75
IR - 9......................................................
0.74
IR-10....................................................
0.74
TABLE
3
weighted average
0.712
0.675
0.610
0.587
0.586
0.789
0.743
0.742
0.737
P E R F O R M A N C E O F T W O 101,000-SQ-FT
CONDENSERS
SURFACE
V
Heat-transfer
coefficient
(dirty tubes)
Cleanliness
faotor
S
«
£
®
§
£
fc
a
?
jjo v
2 3 1J*
g
£
® c*
§ <o
The paper seems to be the first serious
£
*
£ .£
®
*2 2
° S .§ 8 ’3
t
|
S
£ !§
K
attempt to take into account the condition of surface cleanliness
®
OS?
o f I.
H
Q
m S a wSffl ■<£
O S.2
£.8.2 < g-jg
in reporting condenser tests, especially where units of large size
W-5............
6-13
463
455
0.68
0.685
61.6
0.937
708
are concerned. The thoroughness with which the authors
W-6............
6-14
448
463
0.61
0.597
62.7
0.947
819
W-9............
6-14
436
459
0.59
0.577
61.9
0.940
846
have conducted their tests and the painstaking care which they
W-10..........
6-14
419
432
0.59
0.568
61.4
0.935
813
have exercised in planning and completing their work should
IR - 5...........
6-27
591
553
0.78
0.794
67.3
0.984
708
6-28
581
563
0.75
0.758
68.5
0.992
749
IR - 6...........
lend a high degree of credibility to the results which they publish.
IR - 9...........
6-28
590
576
0.74
0.746
68.2
0.990
780
IR-10.........
6-28
571
551
0.74
0.749
67.6
0.988
746
Consideration of the cleanliness factor in appraising the per­
formance of a condenser is extremely important, because without
Hodgkinson, we note a remarkably close agreement, as indicated
definite information as to the magnitude of this factor, no con­
in Table 2.
clusive significance can be attached to any condenser test results.
In stating their conclusion, the authors say they “ doubt the
An examination of the data in the Hardie and Cooper paper
does, however, throw some light on the possible explanation of
soundness of the cleanliness correction for making accurate
the small discrepancy to which the authors call attention. I t
comparisons where large differences are involved,” and “recent
will be noted that for some of the tests reported, noticeably
test work confirms the inaccuracy of a straight-line cleanliness
correction.”
those on the Ingersoll units, the average heat-transfer coefficient
It would seem that what the authors mean to say is that the
for the dirty tubes in the selected sample groups does not co­
correction factor applying to any selected group of sample tubes
incide with the average coefficient for the entire condenser, the
within a condenser cannot be taken with absolute assurance to
margin in some cases being of considerable proportions. In the
case of the Worthington tests, the margin of difference is very
represent the actual cleanliness factor of the entire condenser.
No one would question the
straight-line relationship of the
cleanliness correction in so far
as the selected groups of sample
tubes is concerned except for
any small change in steam dis­
tribution within the condenser
which m ig ht accompany
changes in heat transmittance
at any given load. This, how­
ever, is a factor which need
not be discussed at this time.
W hat we are really interested
in is an examination of the
data reported by the authors
to see how closely the factor
reported for the selected groups
of tubes represents the cor­
F i g . 13 R e l a t io n B e t w e e n C l e a n l i n e s s F a c t o r a n d C o e f f ic i e n t o f H e a t T r a n s f e r a s
responding factor for the entire
A f f e c t e d b y P o s it io n i n C o n d e n s e r
condenser.
Various sugges­
tions have been made to the
Power Test Code Committee for securing the best possible aver­
much smaller, all of which is shown by columns 3 and 4 in
Table 3.
age of the various sample tubes selected. Mr. Hodgkinson has
I t is apparent, therefore, that if we know the relationship be­
suggested an average weighted to account for any variation in
tween cleanliness factor and coefficient of heat transfer for a
rate at which the various tubes may be working. The authors
tube of given cleanliness, we can calculate from the factor actually
have preferred to use the arithmetical mean. If we refer back
measured on the selected groups of sample tubes the actual factor
to the paper by Messrs. Hardie and Cooper presented in Novem­
for the entire condenser in order to correct for the discrepancy
ber, 1932, and recalculate the average as suggested by Mr.
10 Chief Consulting Engineer, Worthington Pump and Machinery noted. This relationship is discussed in the paper by Mr.
Townsend Tinker at the A.S.M.E. meeting, Chicago, June, 1933,
Corp.. New York. N. Y. Mem. A.S.M.E.
Paul D
i s e b e n s . 10
FUELS AND STEAM POWER
and need not be enlarged upon here. I t will be interesting to
note, however, that experimental data reported by Messrs. Hardie
and Cooper applying to the identical tests reported by the
authors of this paper clearly show this relationship. Fig. 13 has
been plotted from the data covering tests Nos. IR-9, W-9, IR-8,
and W-8. Certain of the tests at lower capacity do not indicate
this relationship quite so clearly, but we may assume that the
decrease in cleanliness factor is directly proportional to the heat
transmittance as indicated in Fig. 13, and this therefore gives us
a basis for calculating the true cleanliness factor for the entire
condenser based on the cleanliness factor as measured in the
F i g . 14
C o m p a r is o n o f P e r f o r m a n c e , W o r t h in g t o n C o r r e c t e d
t o I n g e r s o l i ^ R a n d C o n d it io n s
selected groups of sample tubes. In Table 3, the factors as re­
ported and corrected are in columns 5 and 6.
While the modification as calculated may seem small, it is
nevertheless of sufficient magnitude to account largely for the
discrepancy reported by the authors, all of which will be ap­
parent upon referring to Fig. 14. I t should be noted that test
No. W-l has been omitted, because during this test as reported
by the authors air leakage was excessive.
I t is hoped that the analysis of the authors’ data which the
writer has given will assist in enhancing the credibility of their
methods for measuring cleanliness factor. Their experience in
conducting tests of this character will be of great assistance to the
committee now engaged in considering the possibility of including
a condenser cleanliness factor in the Power Test Code.
C. L. W a d d e l l . 11 This paper states that the tests conducted
by the Brooklyn Edison Company and reported in detail by
Messrs. Hardie and Cooper determined the “cleanliness ratio”
of the condensing surface. In reality, the tests only established
the “cleanliness ratio” for the selected tubes. The tests do,
however, give us all the necessary data to determine very ac­
curately the true “cleanliness ratio” for the entire condensing
surface by calculation. This correction has been covered by
Mr. Diserens in his discussion.
The paper states that the condenser manufacturers made
guarantees which were to be corrected downward from 100 per
cent clean transmittance guarantee in direct proportion to the
“ cleanliness ratio” obtaining at the time of the test. Using the
authors’ definition of “cleanliness ratio,” it would seem from
11 Test Engineer, Worthington Pump & Machy. Corp., Harrison,
N. J.
FSP-56-3
175
Mr. Diserens’ discussion that this method of correcting guaran­
tees for cleanliness might either be unfair to the buyer or the
manufacturer of the condenser. If the average heat-transfer
coefficient for the selected tubes is higher than for the entire
condenser, the cleanliness ratio as determined by the tests would
be unfair to the buyer of the condenser, because the tests would
show better performance than was actually obtaining. If the
average heat-transfer coefficient for the selected tubes is lower
than for the entire condenser, it would be unfair to the manu­
facturer of the condenser, because the tests would show poorer
performance than was actually obtaining. I t is therefore neces­
sary to correct the cleanliness ratio in the manner suggested by
Mr. Diserens to obtain the true performance.
The graphs by Mr. Diserens show that all the actual test
points on the dirty tubes are at fairly high heat transfer. He
has assumed a straight-line variation between the average of
these points and the point of 100 per cent cleanliness factor and
zero heat-transfer coefficient. We must take into account that
the correction is small where the location of the selected tubes is
such that their average heat-transfer coefficient is close to that
for the entire condenser. Therefore, it is not only permissible
but logical to assume the straight-line relationship for these
small corrections.
The Subcommittee on Condenser Tests of the Power Test
Code Committee recommended tentatively in its report dated
Sept. 24, 1932, the type of test for obtaining condenser cleanliness
factor as covered by this paper. No mention was made in these
recommendations as to the maximum allowable variation be­
tween average heat-transfer coefficient for the selected tubes and
for the entire condenser. In the light of the data in this paper
and the discussion upon it, it would appear advisable for the
Power Test Code Committee to consider limiting this variation.
It is suggested that the allowable variation be set at 5 per cent
plus or minus, and when the variation exceeds this amount, that
the test-tube locations be changed to bring the results within this
limitation.
The curves for heat-transfer coefficient and absolute pressure
shown in this paper do not show the actual test points and are
not corrected for differences between average heat-transfer
coefficient for the selected tubes and for the entire condenser.
When the test points are plotted without this correction, they
do not fall as nearly on the curve as they do with the correction
as shown by Mr. Diserens’ figure. This further substantiates
the writer’s belief that this correction is desirable in a proper
interpretation of the test data.
I t might be well to outline in detail the method for correcting
the test data to obtain the true cleanliness factor for the entire
condenser:
(a) Average the cleanliness factors for the selected dirty
tubes.
(b) Average the heat-transfer coefficients for the selected
dirty tubes and check to see whether this is within 5 per cent
plus or minus of the heat-transfer coefficient for the entire con­
denser.
(c) Plot the average heat-transfer coefficient for the selected
dirty tubes as abscissa against the average cleanliness factor for
the selected dirty tubes as ordinates.
(d) Draw a straight line from this point to the point of 100
per cent cleanliness and zero heat-transfer coefficient.
(e) Read up from the average heat-transfer coefficient to this
straight line to obtain the true cleanliness factor for the entire
condenser.
A
uthors’
C
losu re
Mr. Bancel’s comments are in the nature of an addition to the
paper and call for no comment by the authors.
176
TRANSACTIONS OF THE AMERICAN SOCIETY OF MECHANICAL ENGINEERS
The discussion offered by Mr. Harwood shows a computed
curve of performance for the Worthington condenser corrected
to the Ingersoll-Rand test conditions. The authors can neither
substantiate nor repudiate the correctness of this computation
by test fact. The corrections employed for water velocity and
water temperature are generally accepted and are of relatively
small importance to the comparison. The correction for tube
cleanliness in direct proportion to the cleanliness factors reported
is entirely in agreement with the correction factor relationship
which forms a part of each contract, but which is subject to
question.
The authors have in hand some additional data from a series
of test runs made in connection with an entirely independent
investigation of the accuracy of sampling possible with isolated
test tubes. These runs were at lower water temperature and
lower cleanliness ratio than either of the acceptance tests re­
ported in the paper. Since the Ingersoll-Rand acceptance test
was made at higher water temperature and higher cleanliness ratio
than the Worthington test, a sort of interpolation of the IngersollRand performance is now possible.
This interpolation is limited in that the recent runs were made
only in low circulating-pump speed and in that the two variable
elements in the comparison—the water temperature and the
cleanliness ratio— cannot be separated from each other without
assuming that the manufacturer’s correction for temperature
holds for the performance of this Ingersoll-Rand condenser.
Such an interpolation, when performed on the Ingersoll-Rand
heat transmittance coefficient, shows that substantially no differ­
ence in performance would exist between the condensers were
they both to be tested under the conditions existing at the time of
the Worthington test.
In drawing a comparison between the Westinghouse No. 6 con­
denser at Hudson Avenue and the tests reported in this paper,
Mr. Morgan is using commercial correction factors to an even
greater extent than is required to compare the Worthington and
Ingersoll-Rand units. The authors have stated in the paper that
they have hesitated to use such correction factors not supported
by their own test work on the specific condenser to which the
correction is applied, and for this reason can make no further
comment on Mr. Morgan’s discussion.
Mr. Diserens, in his discussion, calls attention to the fact of
position of isolated test tubes in the condenser affecting the
cleanliness ratio even when assuming a specific condition of dirt
film common to all tubes. Tubes near the steam inlet having
high heat-transfer rates are adversely affected by a given dirt film
to a greater extent than those near the air offtake whose heattransfer rate is relatively lower. Mr. Tinker’s paper contains
an analysis which can be applied to the explanation of this fact.
Our test work attempted to eliminate the necessity for a cor­
rection such as Mr. Diserens has suggested by an initial selection
of test tubes such that the average heat transmittance of the
isolated tubes would be as near as possible to the average of the
entire condenser. The degree of success with which this has
been accomplished is shown by the very small magnitude of Mr.
Diserens’ correction.
A refinement is necessary to the computation of the IngersollRand results in Table 3 before a true comparison is possible.
Mr. Diserens’ values for sample-tube averages are based on tem­
perature differences between the circulating water in the tube
and the estimated temperature of the steam surrounding the tube
as presented in the Hardie and Cooper paper for comparison of
isolated tube performance. For comparison of isolated tube
performance with overall condenser transmittance, the authors
prefer to use the temperature of steam at the condenser inlet.
When transmittance coefficients are computed on this basis, the
sample tube averages are found much closer to the average for
the entire condenser.
Since the receipt of Mr. Diserens’ discussion, the authors have
plotted the results of the additional test work previously referred
to in a manner similar to Fig. 13. This data would not justify
the straight lines projected through to 100 per cent cleanliness
factor at zero heat transmittance, as shown in Fig. 13.
The authors take this opportunity to acknowledge the value
of Mr. Diserens’ analyses and will utilize additional data as they
become available to establish by test fact the principles he has
pointed out.
At the present time the authors do not have sufficient informa­
tion to justify endorsing Mr. Waddell’s proposed method for
correcting test data. It does appear highly desirable, as he has
pointed out, to select the isolated tube groups so that the average
of the isolated-tube heat-transfer rates shall be as close as pos­
sible to the average for the entire condenser. As will be seen
from the comparisons brought out in Mr. Diserens’ discussion,
these correction factors will be quite small when the average
transmittance of the isolated tubes and that of the entire con­
denser are nearly alike.