IlSS. lSTITlJTE
........
'j
I
FOREWORD.
Thanks
for'
are .due to Brown
courtesies extended
us
&
Sharpe 1,Pfig
I
Co.
in the preparation of 'this
thesis.
We desire to make especial" mention of the
assistance afforded us by Mr. W. T. Hatch, Chief Enginear of th,sCompany, Mr. Henry
H.
Fales, formerly
Assistant Engineer, and Mr. vrm. l\laclanachan,
Chief
Electrician.
Respectfully
Mass. Inst. of Tech.
t'lay 20, 1911.
submitted,
.
Sw,'tC/n
Ce-ntral
bO<:1'rd
Po
W"~r
Pia nt.
CO"X
~21IRt'C/e
SClryea
n
e d t'n C en
-JO
Re. /n s t t:f
/ /
R we-r Plant
r En 9/n..err I
a
Bo//er
R
. S "Coj(ers
(Jom/
C e /7
rShovY
and
Irc;p I PC; tA/.er
/n q
We f9h /n;l
PIC(
1ro,P,P e
r;-
J]
t
I,
The purpose of this thesis is to show what advantages are deri ''red from the use of' electric instea.d of
steam drive in~l Building.
In order to present the sit-
uation clearly it ~Nillbe nece seary to give a brief description of the ata.te of affairs that exi stan at the
plant early in 1910.
At that time the Bro\~ & Sharpe Mfg. Co. was maintaining fiTe separate power plants, each of which supplied
a distinct group of buildings with heat and power.
In
all cases the engine which provic.ed power to the building
was located on the first floor or basement.
The boilers
also occupied space that was extremely valuable for manufacturing purposes.'
The labor costs were very high,
since each engine required an engineer and in some cases
an assistant, and each set of boilers at least two atokera.
Arte r consiciering carefull:.vthe advantage sand
disadvantages of the isolated power plants, the Company
decided to consolidate four of them into one central plant.
The fifth because of its isolation from the central plant
was not included in the plan.
Some of the advantages
which are hoped to be derived from the consolidation of
the plants are as follows:- the large plant with electric
driTe will make possible a great reduction in labor expenses; it will make possible econornica.loperation of automatic stokers, and thus allow the use of low-grade coal
without excessive smoke; it will eliminate the losses due
to the belts from the enginesto the floors; and will make
available for manufacturing purposes a.large amount of
floor space now occupied by the boilers and engines; it.
will allow the operation overtime of separate buildings,
without necessitating
the use of an engine in each of the
buildings, during the period, but instead the load may be
carried by one or more engines working at full load and
under the charge of fewer engineers than was possible under the fornler conditions.
The present plana call for the removal of the reciprocating engines from the isolated plants to the central
plant, where they will be used to drive 230;volt,3M~,A.Ce
generators.
steam
nator.
The'exhaust will be utilized in an exhaust
turbine coupled to a 750-k.vre,
240-volt,
60~
alter-
It was hoped that this plant would be completed
in time so that the cost of electrical power supplied to #4
building could be determined, but owing to delays incident
to the delivery of apparatus this cost cannot be determined,
and it will be assumed that the power is to be obtained
:from the narragansett
Electric
Lighting Co
e
The power plant, which supplied the po~rer to #4
8,
Building,
ma3r
be briefly de scribed as follows: - In a boil-
er room 60' x ?5' there are installed two Stirling boilers
of 200 B.H.P. each, designed to supply steam at 150 lbs.
and 100 degrees superheat.
The boilers were hand fired,
and were equipped with a fan so arranged as to aid the
draft caused by the stack ~lIhenit fell belo'",.
a fixed value.
These boilers yrero installed in 1906, and at the
tiXIlG
of this
\
teat were in excellent condition, although in need of
cleaning.
.
Two Harrison boilers, installed about 1885, were
used to supply st~wn for heating
and for running the ele-
vator plOOp, while the two Stirling boilers delivered steam
to the engine, which supplied the power to the building.
In the engine room, 56' x 24', there was installed in
1900 a 20~ x 42ft Rice and Sargent simple non-condensing
steam engine.
This delivered abont 300 R.P. at 90 R.P.M.
The ex-~aust was led to a feed water heater, which heated
the feed to about 80 degrees Centigrade.
lIone of the ex-
hau'st from the engine \Vas used again in the boilers.
Power was transmitted to the six ~loor8 of the
building by means of belting and jack shafts.
On each
floor friction clutches were placed between the line and
jack shafts, in order that a certain portion of the floor
could be thro'\m off if nece Bsary.
In operating #4 Building electrically
three differ-
ent plans were considered; the first. was to install one
motor of about 300 R.P. to driTe the entire mill; the second waa to use individual driTe) anci the last, group
drive.
TIle first was deemed impracticable,
since the
space occupied by the jack shafts and beltinr; woule..not be
available for mm1ufacturing
purposes, and since the loss
in the jack shafts, which was about 25% of the total load,
would not be eliminated by this method.
necessitated
The second plan
costly changes in the. arrangement of the line
shafting, and called for the throwing out of moat of it,
and would cause serious interruption
to the continuous op-
eration of the machines.
The last pltm, nmnely the group driTe, was considered to be the best for this building,
sult in no interruption
would eliminate
If
since it would re-
in the operation of the plant, and
the jack shafts
and jack shaft belting.
the bUilding had been new and the'machine s not
yet in operation, there is no doubt but that individual
drive would have been used, since its use results in a better power factor for the system, and a saving of power,
since belting losses are practically eliminated.
In order to determine what motors should be installed on the different floors, a 3q R.P. motor was used
to drive the separate line shafts, and the input noted
of a Westinghouse
the Engineering
Graphic Wattmeter.
Department
these investigations
by
This work was done
of the company.
means
by
As a result of
it was decided to install the follow-
ing motors on the various floors:~
On the first floor, one
25 R.P. and 'one 10 H.P.; on the second floor, one 35 Ff..P~~;
on the third , one~5
R.P. and one 5 R.P.; on the fourth,
one 50 H.P. and one 5 H.P.; on the fifth, one 35 H.P., two
20 H.P., and one 15 H.P.; and en the sixth, two 50 H.P.,
one 20 H.P., and one 25 R.P.
This makes a total of 380 H.P.
These motors were manufactured
'tric Company, and were 230-volt,
quipped
T,vi th
3-f
by
the General Elec-
Induction motors, e-
starting compensators and overload release.
Current was supplied from the feeder panel at the
power house thro~h
Building.
cables to the various f~oors of #4
Fuses were place~ in the feeder panels, and
also on the generator
bf.l.t no circuit breakerd
side of each starting c~npensator,
were used in the line other than
those at the feeder panels and the compensator boxes.
Before the steam plant was removed,
opportunity ';vas
offered to get data for the operation of the machinery
by
steam •
For any comparison of stemn and electric drive in
thi mill it is necessary to know the ~team Horse-power
quired to run it during the average
re-
day, and the coal and
s
water used.
To find out if the boiler is operating at
good efficiency a bo~ler test must be made also.
The load on the engine was found
by
taking indicator
cards at frequent intervals throughout three days.
Two tests on the steam plant were made; one with the
boilers (Stirling) supplying the engine alone, and one with
the boilers supplying the auxiliaries and engine.
The pur-
posa of the first test was to get the efficiency of the
engine, and that of the boilers, and that of the second to
get the amount of coal and water used in the boilers to
supply steam to the auxiliaries and engine.
In order to obtain roughly the horse-power delivered
to each of the six floors the following method was used.
With all the fioors in operation indicator cards were taken
at the engine, then the sixth floor was throvm off
of the clutch
connecting
the line to the jack shaft,
indicator carda again taken.
by
means
and
The difference between the
two engine I.R.P. was the R.P. delivered to floor six, plus
the friction losses due to the transmission of this po~rer
to that floor.
Then the clutch was again thrown in, and
the operation repeated for all the other floors in turn.
To determine the efficiency of the engine and also
to determine the thermal efficiency of the boilers, a test
was made
On
the engine and boilers.
During this test the
auxiliaries were r2n by the set of Harrison boilers, and
steam was delivered from the Stirling boilers to the engine
alone.
This was lnade necessary by the fact that there was
no means of weighing the eXhaust from the engine, and the
only practicable way of dete~ining
was by measuring
tm
the steam consumption
the \vater fed to the boile
}~6.
To do this
feed water pipe line was cut and a barrel was arranged
to receive the water fro~ the feed water heater placed in ~he
exhaust pipe.
After being weighed the water was allowed
to ,flo.~l
into another barrel, whence it \vas dra~m by the
feed pumps and forced into the boilers.
Before the start of the test the fires were allowed
to burn low, and were then thoroughly cleaned.
The teat
was begun at nine o'clock, at which time the barrel supplying the feed pump was full, strings were tied around the
water glasses at the level of the water in the boilers, indicator cards were taken, steam pressure and tempe rature at
tm engine were noted, R.P
"!\~.,
and temperature
of the feed
wate r read.
Readings of the instruments were made ever~' fifteen
minutes from nine to fi~e with the exception of the noon
hour, when the plant was shut down.
A short time before the conclusion of the test the
fires were cleaned, in order that they might be in the same
B,
condition at the conclusion of the test as at the beginning.
At the end of the test care was taken to see that the level
of the water in the boilers was the same as at the start,
and that the barrel supplying
the feed pump was full.
If
this were so the total amount of water fed to t~e boilers
from nine to five was the amount of water poured into the
barrel from the start, when the barrel was fUll, to the
conclusion, when the barrel was again full.
A sL~ilar test was luade on Nov. 9, only in this case
the auxiliaries were also connected to the Stirling boilers!
The purpose of this test was to find the efficiency of the
boiler, and the amount of water and coal used in the boiler
The duration of the test
to furnish steam for the engine.
was the same as the first, but readings were taken every
half' hour.
The coal used during each test was carefully weighe4
the.
as was also the case in regard to 11 ashes.
The heating value of the coal was obtained by tests
made by the engineering department
lJIanufacturing Compan:{.
of the Brown & Sharpe
Barometer readings were obtained
rram the United states Weather Bureau office at Providence,
located adjacent to the plan,t.
All instruments
u.sed in the tests were calibrated.
The steam pressure gage was tested
by means
of a Cro8b~r
s
gage
testing
device;
by inserting
the engine
the bulb
in a bath
states Goverrunent tested
The bath was gradually
stirred
t'~10
by means
thermometers
maxi~,~ point
lowed
heated,
thermometer
device,
temperature
was noted
of the Massachusetts
with
a government
The Crosby
at the factory
accurate
of the thennom-
This method
Calibration
in this report.
was made
of this t~~e,-
is very sluggiSh
of which
calibrated
Institute
neceswith a
in its action.
the feed water
in the h.eat laboratory
of, Technology~
by comparison
standard.
steam engine
of the Crosby
to within
the
and readings
by means
Vias
When
the bath was al-
aary by the fact that a thennometer
The thermometer
of the
was reached
taken as before.
tube bent at right angles,-
tho~oughly
and readings
at the same time.
of calibration
a United
was placed.
the oil was kept
of a stirring
were noted
was calibrated
of oil in which
standard
to cool off gradually,
sters were
thermometer
indicators
cmnpany,
wera calibrated
and were found
to be
two percent.
curves
of all instruments
will be found
/0
Before
portunity
the installation
Vias offered
at the pOVler
tion of a Westinghouse
Bupplying
4th,
floors
102.7 R.P.
Sinca
house
wattmeter
steam,
by the watmeter
input as measured
i.e., 87.4 R.P.
it was decided
opporttmity
was no longer
of the wattmeter,
result
to check
offered
checked
so arran~ed
for the insertion
each one of the four motors
which
a~ainst
the sixth floor.
times
this floor was checked
was 114.3 R.P.,
the
Due to the fact
the feed panel had been between
separately
in the feeder
respectiTe1y.
wnat was expected,
op-
for the insar-
1, 2, and 3, and in thoJe supplying
that the sixth floor
that
graphic
5th, and 6th floors
was far below
of the new s~itchboard
by indicating
installed.
with
The
the 102.7 H.P.
for stea~m driving.
The graphic
Wattmeter
in series with a General
The two were
meter.
the lar.t'1'est
available
o
Tolts
and amperes
accurac~
Electric
)
calibrating
current,
weight
tain distance
watt-hour
Readings
were made with instruments
wattmeter
BO
the power
of knovm
with
a small
arranged that with voltage,
the indicating
point
of
factor.
is provided
\7e igh
placed
11ith a 50 H.P. motor,
for three hours.
on the mete r, e.nd the
the apparatus,
b~y being
recording
run in series
in order to obtain
The graphic
was checked
but no
t hung on an arm on
should
from the edge of the paper,
travel
a cer-
and stay there.
If.
This calibration was tried, B.nd the mete r fulfilled the
above condition in each case.
However, its readings did
not agree with those of the General Electric meter, which
had just
been ca.libra.tedby the General Electric Compan~;.
This Integrating meter ,yas also tested in the Engineering
Laboratories .of the Massachusetts
&y.
Institute of Technolo-
It was ce.librated as a single phase meter, as sug-
gested in its accompanying
instnlction book, with the
current coils in series, and the potential coils in parallel.
A voltage y{as obt~tined approximately
equal to
the voltage at the Bro~m & Sharpe Mfg. Company's
a.nd the Bame current was used.
varied from 0.50 to 1.00..
plant,
The power factor VIas
Variations in power factor
were obtained by different division of the load between
reactance and resistance coils.
Plota of this test will be found appended.
The integrating meter was compared with a standard
instrument of the Standardizing Laborato~r,
to be correct.
Graphic Wattmeter
The indicated error of the Westinghouse
was then detennined
its readings were multiplieu
seems to be a ve~i
and was found
as .5lit,
50
by 1.51 throughout.
that
This
large correction, but is justifiable.
The total electric input, corrected, is seen to be larger than the consumption from the steam engine, and the
12,
expected
ination
saving of 78.4 R.P.
page2/,
that the electrical
figures
power house to the building.
%
tracted
a 10
voltage
between
motor
elim-
Show input from
From this must be sub-
line loss, obtained
station and motors,
by noting
the drop in
and about 13
% for
inefficiency.
The efficiency
manufacturers,
Allowing
of these
motors,
is from 86 to 89
a.s quoted
bji the
%.
for these losses we find the electrical
output ve ry nearl~/ equal
minus
) from the
of the jack shafting may seem lost, but it must
be remembered
the
(see
to the
the belt and shafting
stearn horse
losses.
po\ver output,
13,
LOAD ON NOV.?,
Time
1910
R.P.
11:40
11:55
2:00
2:30
2:45
3:00
3:30
4:00
4:30
5:00
5:30
314.0
286.0
298.?
295.?
308.3
302.1
284.0
290.6
28?8
284.1
285.?
:323T:tf
av.
294.3
Average
R.P. l:rov. 7
294.3
Average
lI.F. Jrov.
295.9
Average
R.P.
1Tov.9
287.6
877.8
Average
for 3
days
292.6
14,
TEST OF NOV. 8, 1910
Detennination
of Engine Efficienc~r
Engine alone op boilers
Length
Lbs.
of te at
9 - 5
7 hra.
of water
(Shut
49,507
Iba
1,649
Ibs
Ash
Barometer
29.74"
143.6 F
=!/--#2Buckwhe at
steam Temp.
Cost
of Coal
B.T.H.
.12,100
Lbs. of coal
pressure
14.61 1bs
0
Temp of feed
Steam
down from 12-1)
8,580
gage
119.211bs.
414.0
abs.
"F
$3.20 pe r ton
IS
LOG OF lTOV.
Time
8.
TemP6ste~ress.Gage
E.P.
T. F
9:00
9~':.15
9:30
9 :45 .
10:00
10:15
10:30
10:45
11:00
11:15
11:30
11:45
12:00
1:00
1:15
1:30
1:45
2:00
2:15
2:30
2:45
3:00
3:15
3:30
3:45
4:00
4:15
4:30
4:45
5:00
106
104
105
106
107
105
105
105
108
104
108
105
105
102
105
107
106
106
105
105
105
106
107
105
100
104
106
102
104
106
396
399
397
393
392
391
395
399
400
395
390
395
404
355
347
380
396
405
410
407
405
410
412
408
409
412
415
412
423
413
)119"11
-399.03
T3i54
105.13
61.0
58.0
56.0
61.5
62.5
64.0
62.0
65.0
64
64
64
63
63
65
58
64
62
65
60
62
65
63.5
63
60
59
62
62
63.0
64.5
64
)1870.5
62.3
-.5
+15.
corr.414°
287.1
292.8
295.3
296.6
303.9
290.4
308.2
307.1
304.8
290.0
298.0
301.1
28B.4
284.8
305.6
298.2
296.7
294.5
297.3
292.2
301.7
292.5
296.2
285.7
308.3
291.1
284.2
291.8
301.7
) 290.7
)287 6.9
29rr.89
Temp.Feed
Temp.()C
F
corr.l04.6
corr.52.0
-=143.6
"
0
F
0
E
18
Calculations
of Engine
and Boiler
Efficiency
4°507 :':;
.'7 ::;"7072.4 # water per hour
:117.87 # per minute
At p ~ 104.6
Assuming
I,
T ~ 331.l4~,
at atmospheric
B.T.n.
used per
R: 1232 B.T.LT.
back pressure
#
pound of water ~ 1232-179.9
.::.1052
1 R .PI.=-42.42 B. T. n. ,per minute
42.42 .295.9
Engine Eff .~-1.-0027-117.9
-- 10.12
.
Boiler feed temperature
Heat
absorbed
Heat
given up by coal:
62
0
=1120x70~2
14820000
;t
Q62o=111.6
8580 *l2l00
7
i.
C
in :Boilers: 1232-112=
Boiler Eff.
- 14.6
"
=
B.T.D.
1120 B.'I'.U. per lb.
=
53.4
14820000E.ID.U.
%
per hr.
17,
TEST OF NOV. 0, 1910
Boilers supplying Engine and A~~iliaries
Duration
7 hours
of te at
Lbs. of coal
8320 1bs.
Lbs. of ash
1998 1bs.
51900 Ibs.
Lbe. of water
Barometer
Cost
beginning
29.92tl
end
29.90"
14.7 Ibs.
$3.60 net
of coal
13600
B.T.TI.
Temp. of feed
ton
48 .8~ C
119 .gO F
Pressure
119.74//=
Temp. of steam
419.0oF
abs.
IS,
LOG, nOVe 9.
Temp.Steam
Time
of
400
400
402
398
405
400
400
375
400
405
405
400
410
410
425
425
) 6460'
403.8()F
corr. 419°F
9:00
9:30
10:00
10:30
11:00
11:30
12:00
1:00
1:30
2:00
2:30
3:00
3:30
4:00
4:30
5:00
Pres s .gage .
Temp.feed
°C
48
47
47
49
62
HP.
..
287.3
105
290.4
106
283.0
103
282.8
104
29!").5
108
288.5
48
105
283.4
49
105
310.9
39
104
287.0
50
106
298.8
52
108
290.0
50
108
281.3
49
106
285.3
48
105
281.0
49
105
281.8
47
102
:.274.6
49
106
)46-01'.-tf
)168,,4
)783
287.6 HP.
48.93., 0 C
105.4=!Igage
-.4
- • .J..
48 .8-3"D C
105704
14.70
119.'74#abs
JS
PLAUTTEST,NOV.9 (continued)
Boiler
119.74 Ibs.
Pressure
419
Temp.
Temp.corr.to
119.7#
0
341.14
77.80
H
=
877.0
=
122,8.0
=
Total
:B.T.U.
F
t.
312.1
C
superheat
4
~5(77.80)
B • T •IJ •
87.9
=
Equi'V. ETap. from
51,900 · 1140.1
and at
= 532..
212 pe r lb. of coal
21_~q_~O .11~0.}('
__
9 69 •7 • 8, 3 v.
:Boiler
H.F.
11!.~1_21
7.341bs.
,900
7 -33,320.
Thermal Eff.Boiler
000000
253.5
BlIP.
1140.1 • 51,900
8320 - 13, 600.
52.25
%
PLMTT TEST, NOV. 9, (cont.).
Total 1bs. of watero
per hr.from and at 212 F
to be evap.for 287.6 HP.
=
1228
144
1084.
1084 • 51900
~.
g69~~~)-
8300 Ibs. of water from and at 212°F
- for 287.6 HP.
Assume 292 HP. as average load.
292 2R? • 6 ...,.
1.015
1.015
• 8300
=
8430 Ibs. of water per hour fram and
cJ
at 212 F for 292 HP.
Lbs. of coal per hour -
1bs. _o.!~~~~-Io'-~~.!~r
equ.L.
\,.e vap;_
= 8430
7.34
•
1150 1bs.
292.!ll'.
2/,
DISTRIBUTION
OF LOAD
Steam
No load but sha~ts (machines idle)
163.4 liP.
Clutches throvm out, with gen. carr~ing 120 v 130 am~04.5 HP.
(=
=
Shafting
104.5 - 26.9
Full load
6th floor off
Full load
5th floor off
Full load
4th floor off
Full load
3rd floor off
Full load
2nd floor off
Full load
1st floor off
26.9
HP)
78.4 B:P.
lIP
301.1 HP
204.1
295.7
255.3
97.0 HP 6th.
40.4
5th.
260.3
47•3
260.3
291.7
290.1
294.7
1.6
262.829-9-.8
284.6
31.9
1,2,3,floors
4th floor
KY. unco~
90 ~ installed
'55 HP
~
5th
ft
90 1m
ft
6th.ft
145 HP
ft
6th floor Motors indicated singly
1st
15.2
KH. cor~
37.9
3rd.
2nd.
223.4
Electriaal
4th,
BP.
RP cor~
57.4
77.
35.2
47.2
44.65
59.9
68..
18
8~T4
85.25 114.3
2~~F0V298.4
23.25
29.5
43.
Total
HP
liP
VI alone
Motor
50 RP
50
25
20
Uncorrected
19.60
20,:90
4.59
6.10
51.19 KW
•
77.5
,J.(N
corrected
=
=
103.9 HP
+ 10 % line losS
114.3 HP
22,
DISCUSSION OF LOP~ DISTRIBUTION
Wi th all the machines
the engine
With
the floor
clutches
w1d
a load
the IHP
and 120 volts,
to be equal
Thus the IRP required
or in other words
out
26.1 was due to the generator,
st~ing its efficiency
engine
thro~~
of 130 amperes
of which
to 80
to drive
the shafting
to the clutches
on
the IEF was 163.4
was the shafting,
on the generator
was 104.5,
idle, when the onl~{ load
%.
the jack
and belting
on the various
aa-
shaft,
fram the
floors,
is equal
to 104.5 - 26.1 ~ 78.4 HP.
The total RP delivered to the floors, a.ccording
to the data obtained
by throwing
cession,
equals
223.4 HP.
required
to drive the jack
out each floor
This addeR
shafts
in
8UC-
to the power
• 301.8 h~, which
is
very near to the actual IHP of the engine when under
full load.
The power requireu to drive the various floors
is as follows:
steam
Electric
Electric less
77.0 F:P
57.8 HP
3°5.4
37.3
47.2
4
59.9
40.4
44.9
5
97.0
85.9
114.3
6
298.4224.0
HP
223.4
15 'it.
l'Iotor 10s6 Ylhen run at about 85 % eff.
Line 10s8
10 ~
1,2,& 3
Total loas
48.7
EP
20/0
.
Thus it is evident that the input of power determined by the electrical measurements
is consistent
with that determined from the readings of the steam
Horse Power required.
The electrica~ input was obtained from the Graphic Wattmeter trace bJ: noting
a sufficient
number of or-
dinates, taken at equal intervals, for each curve.
On the twenty-five horse power motor curve the ordinates chosen were closer together than on the other
curves which were more regular.
We feel justified in considering these readings
as trul:y representative
of the
average
day
because the:y"
show such a marked uniformity.
The foremen in the building
all agreed that on
the days of test the floors were all running under normal load.
•
24
OF COST S OF STE.A];I PO}lTER'
CALCULATI02T
Hours running
Plant is shut down 2 weeks for repairs
50 weeks ~ 5 days of 10 hrs
50 weeks
1 day bf 5 brs
2500. hra
250 .....
2750.
60.
269-0:
6 holidays
Total working
hours per year
Coal and Water used
Lbs of coal per year
2690xl150, • 3,090,000.
Assume 5.1bs of coal per BEl' per day
used for banking
5xl.015(253.5)(365.)
Banking coal
2000.
. Total
112.8
1664. t QnJ'.
coal
199B
8320
24 ~
Ash = 24% of 1664
Lbs of water per year
Ash
1545.tons
51~OO 2690
A~ount of water in 1000 gal per year
=
19,950,000
2,388
M. gal,
Operating
Costs
Wa.ter pe r ~rear @
$ .20 per 1000 gal
2,388 x .20
Oil and W'aste @ .033
per IRP hr
.033
Ash Removal @ 25
i
i
(292)(2690)
ton
t per
399 x $.25
Coal per year
$477.6
259.4
99.8
.
.
1664 tons @ $3.60 per ton
5980.
399.tons.
Ibs
Investment Cost of steam Plant
2 Stirling Boilers, 400 EHP @ $13 per BHP
installed
Piping
Auxiliaries (feed pump and heater)
5200.
2000.
850.
Engine, Simple Non-condensing 20 x42rt
Rice &
8000.
Sargent Installed
900.
Stack @ 2.25 per BHP
--1
[)950.
Total Value of Installation
rt
Fixe d Charge 6
847.5
Interest @ 5 % on 16,950
1695.0
Profit, 10
on 16,950
339.0
Insurance
and Taxes, a.Bstwing 2 %
Amortization on Boiler, 1.5 J~ for 30 year
108.
life
25.5
n
on Auxiliaries 3% for 20 yrs.life
120.
n
rt
Engine, 1.5% for 30 yr.life
4.5
rt
n
Stack, .5% for 50 yr life
~139.5
Total
%
--
Ope rating Cost s
Coal, 1664 tons @ 3.60 per ton
Water, 2,388,000 gal. @ $.20 per M.gal.
Oil and Waste, .033 per IEF hr
Repairs @ 2 % of Investment
1 Engineer, 50 weeks @ ~18.00
1 Assistant Engineer @ $15.00
1 Fireman
@ $12.00
Cost~. of Ash removal @ $.25 per ton
5980.
477.6
259.4
339.0
900.0
750.0
600.0
99.8
9405.8
Total Cost per year
1~545 .3
CALCULATION
OF COSTS OF ELECTRICAL
INSTALLATION
Investment Coat of Electric Installation
3 50., HP 900- RP1:tI , 1-8--pole
...Induction Motor @i450• 81350.
,
@ 360.
720.
I 6
fonn K
2 35
1200
2 25
fonn L
"
"
0001.5
603.
/
II
3 20
II
2 15
1 10
2 5
".
"
1800
II
tI
II
II
fI
fI
II
II
I I
@ 277.2 831.6
@ 233.1 466.2
@ 201.6 201.6
@ 71.1 142.2
"
If
I'
!{ 71 pole.
..
rorrl1 C-
Total
Less 10 % discount
. 4314.6
. 431.5
-51'3883-.f
The cost of the motors quoted is the cost installed, a.nd includes the starting compensators.
200.
Wiring
Total coat of installation
~4083.1
Fixed Charges
_
$204.2
Interest @ 5 % on 4,083.1
408.3
Profit 10 % on 4,083.1
81.7
Insurance and taxes, 2
on 4,083.1
408.3
Depreciation @ 10 % on 4,083.1
(Depreciation includes repairs and ob sole Bcence )1102.5
%
Kwh.
=
2690
x
222.5
=
598,500 Kwh per year
Cost of power when supplied to Power House of
Brown & Sharpe Mfg. Co. by Narragansett Electric
Lighting Co.
598,500 Kwh @
a
cents per Kwh
11970
Total cost of Operation of P100lt electrically
l30?2.5
27
DISCUSSIor
If the power
Lighting
Company,
increased
OF ELECTRICflL COSTS
is supplied
to the Power House
and from this supplied
to the mill,
cost incurred through the use of electric
over that of steam drive is the difference
and/12,545.3,
which
If' tlie power
Narragansett
Electric
Sharpe Manufacturing
is supplied
Lighting
directly
Company,
C~pany
%
drive
betweenI13,072.5
to the mill by the
and the 10
%
the cost of
drive is as follows:
loss
$119?0.
119?
107?3.
1102.5
Fixed Char«;es
Total coat of operation of the Plant
e lec t ric all~r
Coat of steam Drive
Cost of Electric DriTe
net saving by the use of electric
line
of the Bro\vn and
is sUbtracted,
Cost in first case
10
the
is $527.2.
loss in the cables from the Power House
electric
by the
$11875.5
12545.3
11875.5
drive-$669.8
DISCUSSION
From the accompanying
but a slight difference
OF RESULTS
data it is seen that there is
in the total cost of power in #4
Building whether the motive power be steam or electricity.
If the Brown and Sharpe Manufacturing
in bu:>ring
Companj-,
power from the 1Tarragans~tt Electric Lighting
Company, dis-
tributed the power from ~ sub-station on the site of their
present new power plant, which, it may be added, they would
not be likely to dO, the cost of the electrical
would exceed that of the steam drive
bjr
drive
$52? .20 per year.
We note, howeTer, that the steam plant was running
at a rather poor economy, as the engine efficiency was only
10.1
%.
A thorough overhauling would doubtless
this efficiencyi
improve
The engine was overhauled before ~ts re-
installation in the new power plant, and it was our intention to detenmine its efficiency under the improved conditions of running, in order to credit to the steam drive
the be st elficienc:'t~obtainable.
second test was impossible,
owing to the non-completion of
the work of re-installing.
operating economy
by
As already noted, this
Whatever gain may be made in
the overhauling
and resetting of the
engine will leave a still greater excess cost chargeable
to the electric installation.
By
subtracting
the line
106ses between the neW' powe r house
29
and #4 Euilding we assume that the Narragansett Electric
Lighting Company is to suppl:y powe r directly to this and
and every other building.
This would undoubtedly
be the
means of distribution, with a transformer at each building
to bring dovm the 1600 volts of the transmission
230 volts for the motors.
line to
The cost of electrical energy
under these conditions would then be less than that of
steam power by ...-;theamount of $669 '.80.
It must be remem-
bered in this connection that the saving due to electrical
drive would be decreased by the increased efficiency of
the ,engine above referred to.
We note here that no better boiler ~fficiency is
considered
obtainable, as the boilers were operating at
the time of the test at an efficiency of 52.8
%,
the aver-
age of the two days.
It VIas hoped,
,as
previovs1jr stated, that the Central
Power Plant would be completed in time for a determination
of the cost to generate a kilowatt hour to be made, but unfortunately
such was not the case.
It is of interest to know what this coat must be in
order that the cost of the electrical drive Shall equal,
but not exceed, that of the former steam drive.
The total cost of steam operation
year.
The electrical
was $12545.30
per
fixed charges a~mount to $1102.50
per year, leaving $12545.30
- 1102.50,
or $11442.80,
allow-
80
able expendi t.urefor 598,500 kilo1;vatthours.
a rate of $11442.80~
This giTes
598,500, or 1.91 cents per kilowatt
hour.
That is, .if the Brovm and Sharpe l~anufacturing
Com-
pany can produce power in the new power house at a cost at
the switchboard of 1.91 cents per kilowatt hour, their
power expenses for #4 Building will be the same as before,
If they can ~enerate at a lower
with the stea~ drive.
cost, the difference will be a pure gain in favor of the
electrical installation.
A point where the electrical drive makes a saving
over the steam is in the matter of floor
tors
uable
are all
space.
on the ceiling,
space.
and therefore occup~r no vC'.l-
The removal of the
eng~ne has made available
on one floor a space measuring 56ft x 24 ft.
tions
The mo-
The founda-
took up a space on the floor below the engine of apl"
proximatel~" the same dimensions.
The removal of boilers
has made available a space measuring 60 ft x 75 ft.
this
space is very valuable for manufacturing
will
800n
All
purpuses,
and
be occupied by machinery.
The bel tine; and pulleys
sho\m in two blue prints
made from Bro\m & Sharpe Compan~lts original drawings,
two disadvantages.
had
They occupied a box-like tube about
seyan feet square, running from the bott~n to the top of
.91
the building.
vailabl~
This, as has been pointed
for manufacturing
leys alse absorbed,
power,
%
These belts and pul-
purpose s.
on the day of the test, 78.4 horse
or in round numbers,
sents about 27
out, is now a-
80 horse power, which
of the steam engine
.This belt 108S is not excessive
at
some other mills
It
could have been decreased
indicated
power •
with that
compared
and factories,
repre-
existing
but is still large.
by the elimination
of the idle
apart of' the main pulley s,
pulley's and the setting further
a
to gain a suitable
arc of belt contact,
but this woule. hIe
taken up too much room.
The use of electric
continuity
of service
drive tends to increase
over that attained
In the latter case injury to the boilers
throw
out of commission
On the other hand,
the entire motive
if the power
tors, an injury to one of the motors
of the plant.
of, because
supplying
or engine would
power
of the m111.
such as electric
mo-
can affect only a
A serious
the supply of pO/fer from the central
unheard
with steam drive.
is not supplied by one u-
ni t, but by a number' of small units
small portion
the
interruption
station
in
is practically
of the fact that the nmlber
of units
the porrer is such that injury to one will affect
but slightl:~r the operation
taeaerl
of the plant.
In moat
case s
employ.A
sUfficientAareA8~Fpli$Q
80
that in case of trouble
in one
1
82
the ot.hersmay be used until the first is in condition again.
Another advantage in the use of electricity is the
decreased fire risk.
The" el~1nation
of the stack, boil-
ers, and engine, also eliminates any danger from oil soaked
waste, or hot ashes.
The electric system is much more flexible than
steam.
In case it is desired to operate
an~y
department
overtime it is nece ssaljr to ntn only the motors of that
department.
had to be on
In case
duty
or
steam drive an engine and fireman
whenever any department was run overtime.
This advantage was particularly noticeable in the case of
the sixth floor, which is almost entirely occupied with
automatic gear cutting machinery.
This department' was
very busy cutting gears for aut~obile8,
overtime until ten.
'.Vith steam drive
anu was working
it would be extreme-
ly doubtful if it would be advisable to require the engineer to work from six o'clock in the morning to ten at
night, or to hire a night engineer and a fireman.
The
engine would also be running at extremely low efficiency,
and consequently the cost of operation wou.ld be excessi va,
but with electric drive overtime work may be carried on at
the same cost as for that done during the regular working
hours.
S3
SUM.EARY
If the cost per ~VH is two cents, electric has no
appreciable advantage over steam drive in regard to cost,
but it does have the ~ollowing markeu advantage5~
1) Eco~om:r of' floor
2)
space.
Elimination of shafts
and
belting to transmit power
fram engine to various floors.
a) Removes a source of danger to employees.
3) Better continuity of service.
4)
Decreased fire risks.
5)
Greater flexibility of plant operation.
a)
Overtime work.
CALIBRATION
OF INSTRIDJffiNTS
Calibration of Engine Thermometer.
Eng ine
The rmom .
standard
Down
Up
375
375
380
385
390
395
400
406
410
415
420
380
385
390
Down
Up
201
205
208
211
213.5
215.8
395
400
405
410
415
21P.
221
224.5
-420
425
425
Degrees F Degrees C Degrees F
DegreesC
Degrees F
227
230
193
195
200
204
206
209
213
216
220.5
394
401
406
412
416
420
424
430
436
440
446
224
230
Calibration of Thenm~aeter ~7666
Toe
Correction
29.0
-.1
64.7
-.3
133.0
161.7
-.1
t.2
Calibration 'of Gage #6932
Gage
st and.Pre as.
85
95
105
110
115
126
125
130
135
140
Up
Down
85
94.7
85
95
105
109.5
115.0
119.8
125.0
129.0
135.0
140.0
106
109
114.5
119.5
125
130
135
140
Corree tion
o
of.15
-.50
".75
1.25
".35
o
+~5
o
o
379
383
392
399
403
408
416
421
429
435
446
3S
Calibration of Integrating Watt~eter #2135368
=
K
Kj. c.oils in
25
in Integrating
.Rev.
20
20
20
20
20
20
20
15
15
20
Time
72.8
62.8
65.0
66.8
75.2
73.0
}r'7.
13.4:8
11.97
12.17
10.37
11.88
11.88
20.0
56.8
56.8
i-15. ~
20.45
20.73
44
20
20
G.E • KW#159;)62
12:.36
14.32
13.85
86.8
43.4
W
I/;:
liultiply reading by 10
Watts
I
205x60
240
220
221
195
196.5
164
194
196
12.30
14.40
13.20
13.26
11.70
11."79
9.84
11.64
11.76
20.10
20.10
20.70
3.025x30
3.2
P.f.
V
~~24 .61
:221 .68
, .228
281
3.1
3.11
.64
.64
.56
222
223.5.55
3.15
3.18
3.05
3.08
3.1
3.0
3.0
3.08
335
335
345
222.5.48
.57
222
222
222
222
222
.57
.99
.99
.99
3600 x 25 Rev
=
-~fI--------
Wattmeter was calibrated
the potential
12.5.
as a single phase meter with
coils in parallel and the currant
coils in
se ries.
Single phase Wattmeter
Current
3:1
#159,362
Reading x 60
Ammete r
#76,986
30 x reading
Vol tmat.e r
#3,770
Transformer
Wattmeter #159,362
partment
.4 watts
was tested by Standardizing
of the Massachusetts
showed an error
#454,802
Institute
of less than one-half
in 127 watts,
largest
error.
of Technology,
of one percent,
Deand
1.e.,
Calibration of Graphic Wattmeter
3 hour run
Integrating wattmeter #2135368
Reading at 12
Readinr: at 9'
00157
00062
3)-9-5- KN
---3T.66
K'.vh
~1Jlrs.:
20.9
Graphic Wattmeter
31.66
Correction = -_.20.9
=
1.513
-a.<~ .
i
0
/1/0
JUt:'.
/fCJO.
'
./60
i
L
:
i
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j
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!
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_ c- p)" 1/
e:
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.
0
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