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Illinois Tnstitute
of Technology
Libraries
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AT 153
Menkin, Jesse Irlis An investigation of the effect of the degree of
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AN INVESTIGATION
OF
THE EFFECT OF THE DEGREE OF SUPERHEAT ON THE ECONOMY OF A MARSH BOILER-FEED PUMP
A THESIS
PRESENTED BY
JESSE IRLIS MENKIN EDWIN HOWARD STILLMAN
PRESIDENT AND FACULTY
OF
ARMOUR INSTITUTE OF TECHNOLOGY
FOR THE DEGREE OF
BACHELOR OF SCIENCE IN MECHANICAL ENGINEERING
HAVING COMPLETED THE PRESCRIBED COURSE OF STUDY IN
«-LINOlS INSTITUTE OFTECHNOLOGV^^^'^'^^'^^ ENGINEERING PAUL V. GALVIN LIBRARY MAY 25, 1 909
35 WEST 33RD STREET CHICAGO, IL 60616
Preface
The sut^ect matter oi thi:: thesis is diviaed into three laein divisions:
Part I states briefly the ob;iect of t.ese tests, and includes a complete doscription •*-' of the apparatur ueed, an explanation of the operation of the pump and the Fisher hydraulic governor, and the ^lethod of ca' librating the in- struments.
Part II includes a description of the meth- od pursued in the 'erforinance of the tests, a discussion of the results, the conclusions dravrn, together v/ith curves, tables and original data.
(a) Tests with Saturated Steam,
(b) Tests 7. ith Superheated ;:5te&m. Part III is devoted to the bibliogrr.-phy.
?ev7 of the articles herein given, apply direct- ly to tests v.ith superheated steam, as ver;/ little material on this subject could be found. The few articles v.hich ap-; ear to be only remote- ly connected with the subject v/ere included
because tliey ccnt;-'in muca V£l-a.:bl8 informaticn rel tive tc tests .v-nd oreration of pumps .
The Appendix cont' ins the s mple calcu- laticns.
The application of surerheated steaifi to pumps has been very limited. Vtjz little investigation has been done alonj-; this line and ccnsequsntly little or not'iiing has been v;rit- ten en the subject. Lore elaborate tests had been pi nned, but o\.inj. to practical aiffi- culties, many of v,hich have be?n overcome, the scope of the v.ork has been limited.
In tho r reparation of the report, especial attention has been tiven to ti:e description of apparatus, and the oreration of the ■ ump and the hydraulic governor. iilretches and photo- graphs h;;Ve been ad:,ed v.jiere they api eared to add clearness. Cnly such t:..bles .nd curves were prepared ?^s seemed necoer- ry to supply the desired in:; ori^ation. The r, mple indica- tor cards shov.n are not intenaed to re-oresent
the averag-e rerfcrmance .f the i^um-n; ti~ey v.'ers iriclii.'ed in order to expl-- in /acre clear- ly the cycle of operation in the two cylinders.
Vie v.ish to e:'i~ress our oblirations to Professor Gt. F, Gebhsrdt, rrofessor of Lecnan- ical iint'ineering- at A. I. T. for many valuable sugfesticns. To Lr. )!1. S. ^ibby, instruc-
tor in Jxreriinental inf-ineoring-, A. J. T., we 0'..e our indebtedness for tiie use cf much au2:il- iary appar-tus. To I-r. J. C. Peebles, instiuc-
tor in Lechanlcal j:;ngineering at A, I. T., we are indebted for his f^ssisttnce in the calibra- tion of the t_:ermom9ters, es' ecially ' for the
res/^tafTce.
use of the plfc-tinum ryrometer and the hi;;-h tem-
A
perature standard. s^'ot the celibration curve of the vonturi meter ..e ov. e our thanl-is to l..essrs. S. J. Aurelius Tnd J. S. Harvey, A. I. T., 'C9. To two of our cl.-ssmates, I.e^srs. F. C. ^anzig and LI. Vanderlrloot , Jr., v'e ex-ress our grati- tude foi the cheerful assist nee '. hich they ren- dered during our tests. V/e are also very much
indebted to l^rs . Julia A. Eevexid; e , librarian at A. I. T., for her kind assistance in miring up xhat little of the "bibliograrhy we herein are c ble to ^resent.
Jesse I. Lenlrin.
Edv/in Jl. Stillman. Chicago, Lay 25, 19C9.
Index lart I.
Ct:'ect Pa^e 1<
Arrar.£eii:er.t cf jLpparatv.s 1.
The i'tiLip 1,
YalT- Geer g,
T/ater Cylinder 5,
Hydr&ulic Gcverr.cr 6'
P.edr,cin£_ lie t ion 7.
The Suxerheater 7 ,
Conoer-ser 9 .
Piping; 9 ,
C al i 1 1 £ t i c n c f In f 1 1 ta::eri t s 1 C , Part II.
Method of Cperaticn IZ .
Tests .ith Saturated Steam 16 .
Discussion, Saturated Huns US.
Tests v/ith Superheated Steam 22 ,
Discn-sion, iiurarheated :\uns 25.
Conclusion 26 <
Part III.
Bihliov-raphy £7.. Appendix
Sample Gslculations
Illixstrrtlong.
Psrt I.
Arrang-GBent of Apparatus 1(a)
Karsh Piimp \vithcut Superheateri' rhcto) lit)
Sectional View of Ilarsh lump 2(a) Fishor Steam Pump Governor (cross-section) 6(a)
Superheater coils (photo) 7Cb)
Detail of Stea:ii Piping' at lump 8(a)
Harsh Pump and Suporheater (i-hoto) 7(a]
Calihraticn of TernonieterSl photo) 11(a)
Part II .
Sample Cards from ateam Cylinder 18(a)
Sample Cords from V/ater Cylinder 18(b)
Curves of Performance (Saturated Tests) 19(a)
Curves of Performance (Superheated Tests) 24(a)
Final Log 24Cb)
Running Log (Saturated Tests) 24(c)
Running Log (Superheated Tests) 24(d)
Average Data from Indicator Cards 24(e)
Part I.
Apparatus .
Calibration of Instruments
Part I.
Obiect
The -rurrose of these tests was to deter- mine the effect of tr^e de, roec of turerheat on the economy of a 2CC-g:llon Larsh toiler-feed pump.
Apparatus
The general 1' yout of apparatus is shown in the slretch on T'-B'S 1(a) . '.^ater v.;..s taken from a reservoir or rump, belo'.. the floor level, and discharged into v.eighing tanlrs or t:.ru a venturi meter. Ste, m was supplied to the pump either from the .i.ain steam line, o, hy-p^^ssed faru the suve.lieater and t erce tu-iraed into tlie pump. The exhaust stetm v.ae led into a sur- face C-naenser end the condensed ctecm v.as pumped into the '.."eirhing tanks shovvn.
The Pump
The "rumr ±v. shown in the Thotcfrarh on rage
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mofAPP/\mu5
iti PUMP TE5T3
rUTE of nCHNOLO&Y J£55EI.MENHIN EDWIN H.6TILLM AN
I Co.)
Ventun Meier
— I 1
Marsh Pump
^weighing Tanks
Superhea ier
^m=rs
AfiRANGEMENTofAPPAmUS rOff MAf^SH PUMP TESTd
ARMOUR INSTITUTE ol TECHN0L06Y
THESIS JESSEIMENHIN
ISOg H'-l' EDWIN H.STILLMm
jLtlsJtWOX'S: Oi' 'XaiOiUMOJuo«X
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Ub)
1(b), whicli v.as taken before ccnnecticn to the suTerheater. It is direct acting, having- a steam cylinder 12" in di meter, a v.ater cjt-i- inder 7-1/4" in di:. meter, end a maximum stroke of 12". Its rated capacity is 216 £.2.11ons per cinute at a sreed of ICO strolres rer minute v/hen operating v/ith a steam pressure of 8C rounds rer souc.re inch gauge against a discharge pressure of 125 pounds per square inch.
The cylinders are separete castings, each cylinder and base or support forming a unit, tlie tv;o units being conr.ected as s'.own in figure on page 2(a). The steam piston is equipred v.ith two met^i-llic packing rings; the v/ater plunger, v.ith hydraulic packing. The tv.o are connected by a br':ss rod l-S/8" in diameter. To the head of the steam cylinder is att:ched a hcllov? brass tube ll/l5" in dicmeter, ..hich eerves as a passage for the .Tteam entering the hollov: riston. A riortion of the iston rod is hcllov;-
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ed out so that the tube has a sliding- fit. From the '.ead end of the v.ater plunder an ll/l5" "br-ss t.- il rod extends thru the cylin.ier head, and cci^rocts to the reducing laech/ nism. The air dome ie connected to a stand ■^ipe, this in turn being' connecteii to a estin:hou£-e air com- pressor. In tliese tests, hcv.ever, the air compressor .as not required.
Yslve Gear
Referring to figure on rag-e E(a), stec.m en- ters the chest O', and ]?«£ ssin^: thru the annular opening A, formed between the reduced neck of the vc-lve an., the chest ass is rrojocted a-^ainst the inner surface of the valve head H, before escaping into the cylinder by means of port r. Both the rssEure cf the staam and the impulse due to its velocity in striking the v^lve head H, f.rce the valve to tha left in the direction of the current, thus tending to close or re-
strict the arr^ul;. r steam TassaLe ii. As t:ie steam ^eaohe.s the cy^inc er, the ^icton it driven to the right. Steam from the cylinder enter- ing po^-t C, flo s urv.i rd into the valve cr-est and exerts a counter ' ressure on tue left side of the Vcilve head h, tenainp- to drive it to th-) right - a movement vhich ■. culd ^Ive g-.i eater port open- ing to the entering chest frcin the chest C. Tie v.lve, therefore, ic al'.ays balanced, and occupies s pcj-ition de-ending uron the relative intensity of the tvo forces v.hich tend to move it in oppc: jte direction — .Adinissicn Steam — vv ich tends to clo:-e it, c.nd Cylinder Steam. v?hich tends, to o--cn it v.ider. Ihis ccnttitutes the ste&m governing eleiiient.
The steam piston conirist, as sho^/n, of a spool form, each head beini-'; proviced i/.ith a metf^lic packing ring, the interior s-^ace R forming b reservoir for live Ete<-m v.hich is supplied from the upper chamber of the steam
-4-
chest by -nrssage li to the cylinder cap S, thence by tube L and the hcllcv, piston V. The vrestvixe cf thie steaw is used only for "tripvin.c;" or reversing the valve by admit- ting ste&m alt ernf-tely ag-ainst tlie outer sur- fr.ces of the vflve heads H thru the ccnr.ecting passages C,C, nef-;r each end of the cj^iinder. The t-iprets T ire ueed for moving the velve by h&nd in case it fi.llE to start automatically.
Water Cylinder
The water cylinder, r_ ge E(a), is divided into two com-'^ertments A and B, heea tnd crank ends. As the y lunger mcves to the left, water is drav.n thru the disc valves A, A, into the Lead end: at the stine time v.ater iE fciced from the crank end thru tlie valves c, c into Chamber C, The mcvenent of the yliinger to the right delivers the head: end chrrge and refills the cran]-: end.
-5 -
The Kydravilic Coyernor
The sl:etch, p£.ge 6(a) shov.-s the i^'isher hydraulic rcvernor. The syring S tends to hold the c cuhle -"balanced v&lve Y off its se&t thus allov,ing- adralssion steam at full fxes'^uie . The presEue of the v.ater in the delivery pipe, trj.nEmltted thru pipe ^ acts on the viston tend- ing to cvercoEie the resistf.nce of tlie s- ling: and close the valve. Hence it is seen that with £:iven steam end discharge pressure, the vrlve v.ill essume some b:-lenced position, snci that any rise or fall in deliv-ry pressure v.ill tend to close or open the valve respectively. If a lov.er delivery head is desired, the re- sistance of the srring can he adjusted by moans of hand v.heel K end lock \7heel L, so that the valve v.ill assume a -^oriticn of rest ^.ith a lov.er water pressure at A. The piston red R is pinned to the sleeve T and the valve stem B which is ri^-idly attached to wheel I, is screv.ed into this sleeve, thereby altering tiie
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FISHER STEAM PUMP GOVERNOR
AHJMtorm
tension of the spring.
Red-acing Lxticn
The reducing mechenism is shov.Ti in the rhctogra-ph on rage 71 a). To the tiil rod is attached a pE.ntogr- ph :.hich trensmits mo- tion to a 5/8" steel rod mounted in suitable bearings, so that its motion is exactly parallel to that of the riston red. Llounted on this rod at points equidistant from the indicate rs are tv;c aluKinuri "finr^ers" to vhich are attached indic&tor cords made ecual in length and as short as possible. Tliu^: 'octh indicators sxe actuated by the ^tme mechanism v.itLcut any aprre- ciable error due to unequal stretch of the cords due to a difference in their len.ths.
The Superheater
The superheater consists of three concen- tric coils of S/4" steel pipe, 10", 2C" , and 28"
-7-
7 (c,)
* .' i
m
F
7(tJ
in diameter, each of lC-l/2 turns. The three ceils are welded together ;::al"ing: 16C' of contir.uous ripe. Steem enters at the top, passes dcv.nward in the cuter coil, ther.ce upvard thru the central coil, dov/nv;ard thru the innermost ceil anc out 't the bottom, to the puiiip. The detail of the steam piping show- in£- the connections to the superheater is sr.ovni on page g, a) . The spaces het'^-een the turns in the coils are partially filled .ith strips of asbestos ..hich serve to deflect the l.eated £Tses and afford a uniform distribution of heat* The coils are turroimded by tv.o sheet iron shells, 5C" and 56" in diameter. The interveing tipace is filled vith cinders to vithin 1" of the top, to rrevent radiation. At this point, around the circumference of the inner shell as a series of I/E" holes vhich allov/ the rroducts of combustion to escape betveen the shells to the stack at top of cover. The coils ere mount- ed on a three-legf^ed circular base about E4" in height. Heat is suprlied by 4 - 4C cubic foot
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S fa)
ll.il. «i ?UU
gas burners feeding :rom a 4" x 3' reservoir ccnrjccted to tv.o s/5" gas Uiains.
Cone-enser
The condenser is a '..'ainrirht surfi.ce con- denser conristin: of 115 tubes 5/8" e:'.ternal, l/£" int /;rnf-l dianieter snd 54.5" in lengtii, nav- ing a steam aurface of 84 scu: re feet and a v/ater surf ce of 67.5 p.nu&re feet. ix 1/2" C":"ening permits venting to the atiiio sphere v.hen condensing at atirc spheric preeeure. A email Harsh pump delivers the condensed eteen; to the weighing tanks.
Piping
The main ste; ni pi": e is l-l/2" in dic.Hieter. The by~pass to the surerhoater is l-l/£" t^nd is connected to the suTerhester by reducing ells. The exxiaust steam pipe is 2" in diameter. The s.ueticn pipe is 4" in diameter end is fitted t ith
_<j_
a gate Vc Ive snc a t'l.erracmeter cup for de- teruiining tho temreratuie of the v.ater.
The discharge rire is 4" at the piimp and reduces to 2" et the tanks. Tc the right of the stand lipe — phctocraph, pa^^e 7(a) ■- a l/£" piT-e from the dischar£,e line tr.'-.nsmits the v.ater pressure tc ore rate the g-cvernor. The £tand pipe is 8" in diameter and 8' hirh. A 1/E" pi-re connects it and tho air doi.:e of the punp, to a '.Vestinf house air cocipressure so that any desired pressure c; n he obtained. During these tests the com-resscr v.ts not used.
Calihration of Instruments
The thermometers used were ill Fahrenhoit and v.ere calibrated agf inet to 8C0° nitrogen bcrosilicate st.rnd&rd. This sttndc-. rd ..as in turn calihr&tec with a plc^tinum resistance py- rometer equipped with a V«"hipple temperature in- dicetor — fl93C — m^de by the Cambridge Scien-
-IC-
tj'fic Instrument CoEp-^::ny. The nitrogen Et&ndr rd v.as fcuno to be correct. The thor- mometers ". ere inserted in e Tortable blsst furnace — see rhctorrBph rarelKa) — which was heeted by a g'as flame.
The venturi meter had been previously cal- ibrated by I^essrs. Aurelius tnd Harvey, A. I.T., '09, v.ho plotted £ Cc librf tion curve . iiich v.as used in tr.ese tests — f:ee tresis of S. J. Aurelius f.nd J. S. Harvey — "Coinpf risen of Ii;fflux Coefficients for various shares end siLes of ilozzles" — .
The pressure grug-es v.'ere calibrated v.ith a Crosby dead-T.eight tester; the s terra gauge v;as found to read 5 rounds too high; the discharge gauge v.as correct. ILe vacuum g- ^i; e v,as cali- 'orated . ith a '.heeler surface condenser and read correctly.
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Ilicv)
The Ta"bor indicator s-^rini-t: v/ere cali- brated in the Ltet-in line sgainst a calibrated steaip £ u; e . Calibration of the srrintie v ere wcde "be fere the stty rated runs, and arain he- fore the FXir-3 rheated runs. The true sc les are indic?:ted on the lo«? sheets.
-IE-
^art II. Lethod.
Tests '..ith batrtrated Steam. Sests 'with SuDerheated Steam,
Part II.
L'ethod
The freneral method v-as to send saturated steam thru the surerhoater v/here it was rj-ised to the desired temperature, thence turned into the puiap. The temperature of the saturated steam v.-as deterinined from the -auge pressure at the throttle; the temperature of su^or - heated steam was determined by me ns of a ther- mometer in steam ripe just before entrance to the gcA-ernor — see sketch, page9(aj— .
A series of rreliniinary tests \;ere made v.ith saturated steam during vhich great diffi- culty v/as experienced in tc:l:ing indicator cards due to e;:cessive pounding in the \.ater cylinder. 3speci-lly v;as this tiue at high rates of seed. It was also found that the weighing tanl'S v/ere of Insiifficiont capacity to handle ! he quantity of v;ater discharged.
-IS-
The slip v;as also excessive being in the neigh- borhood of lu :^er cent. It vas therefore deemed adviscble to overhaul the •^ninp. Ac- cordingly, it was disnantled, the valves ex- amined, and ne.' met llic racking rings were nir.de for it. A nev s rin, ring of l/8" steel v;as iri?:-de for t.ie v/ater ^^lunger ind the hydraulic pacl:in£ v,as renewed . To reduce the ^-ounaing, a l/4" valve wrs pl-rced in the suction line. The ouantitj'- of air thus dravvTi in ..ith the v.t.ter was reduced to a min- imum CO that the consequent decrease in capac- ity was negligible. Cwin.i: to the poor con- dition of the pump the reeult^ of these tests were not kept.
It was origin^ 11:7 planned to mohe a series of performance tests at varying spseds v;ith S-tur:ted steara, t.nd a series of comparative tests at varying speeds with varying def_rees of superheat. After completing the first
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superheated tests it v.ts fcrmd that time .ould not ;^-erii:it carrying out the cririncl rl n. It required from 2-l/2 to 5 hours to --et the temperature of the superheated st%an constant. It v/as, therefore, decided to make the tests v/ith superheated steam at constant speed, vary- ine: only in the decrees of su-^erheat.
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Tests ith oaturated Stoam
Tliese tosts v/ero of 30 minutes dura- tion. Observations v.ere t^lren at int rvals of 10 minutes, of stG;;ii;i, e:Ca .ust and dii^charge [pressures, temperatures in the calorimeter, suction vater &nd room. The steam -rrosKure
was determined hy moans of a steam gsup:e, the exhaust pressure v/as measured hy a vacuum eauge, and the discJhar{:e pressure by a pres- sure g's.ure iiicunted in the disch r~e pipe near the T-.ump. The eteam supply and speed v;ere r-^^rulated by ir.eans of the Fisher gcvei-nor; the discharge pressure v.as m:.intained constant at 60 pounds per square inch by i.ieanG of a v^-lve in the dischar e line. The suction
head \vas me-.sured v;ith a rule at the start and finish of each run, the average being used in the calculations. The quality of stecm
was determined v.ith a throttling c" lorimeter ; the temperature of the water with a thermometer
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inserted in s suit'- ble oil cup plpced in the sucfeion pipe close to the ptunp. The exliaust steam v.as diEchar^ed into a v.ain- right Gurfcce condenser condonsinr at at- mosT^herio -pressure. The steam condensed was pninped into veifhing tanl:s and weighed once during each run. ilo ; ccount vit-s ta- ken of the tem-^'orature nor the weight of cooling v.ater UL-ed in txie condenser.
The water pumTed was delivered to tanlrs and weighed. '..hen the s-eed exceeded 40 strokes per minute, it was found impractioable to V; eigh the water, so thf:-t the venturi Lieter was used. '..hen the capacity bec.s-ue too great for the mercury colunn to hfi.nu.le, a portion of the v/ater from the pump was by- passed to the weighing tanks; the total v;ater pumped, 'being the sxm of v.eighed and metered water.
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Indic^^-tor c; rds v;ere t&Iren siiaultv-necus- ly froLi both cylinders every ten lainutes, in- dividual G-:rds being taken for liead and crant ends, 18(a) , 10i b) .
The speed of the purnp was found by means of a stroke count or attached to t'le tail rod, which registered double strohes. This was read at the start and finish of ecch run.
The ratio of reduction v.as determined by means of a ^- ncil, mounted on the tail rod, which traced a line en a sheet of r.^-or \.hile r.nother line v;as simultaneously drr..wn by the indicator ■ encil. The ratio of the lenrth of the "iston stroke to the length of the line drav/n on the indicator card , on the s?:me stroke , is the re tip of reduction. This ratio v.as determined on the crank end stroke of the v/a- ter c2/.:inder. A g'reat m-ny determinations were made »t various speeds. Tliere was oon-
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Head End dteattiCard 3teain at 71" Superheat
Zl 43 strokes per Minute Scale of Spring 6Z.lh^-l"
16 CoJ)
Hcni End Water Card Steam at JZ" ^Superheat Area-2.04''" Letigih^Zd?" 2/.4J Jtro/re3 per Minute
macHAr^e cnUa Diaehint Beams
5jLi/on Be fins
SuctiOi) £nds
CranK End Water Card 3 tea mat 7Z° Superheat
Area^Z.OO* Letriffh-W ZIA3 jfrokeo per Minute Scale ofSprih^ dJ.^tl"
Discharge Begins
Discha r^e £nds
Suction Bagips
18 ft)
siderable variation, but it followed no general lav/. The avera£,e of these v/as ta]:en as the ■prcbahle true ratio. T'.;is variation is prob'-.TDl;; due to inj-'-erfections in the reducinp- mction or to a sli£,ht "bend- ing of some of itc linlrs.
Discussion
The results of these tests are shov/n graphically by the curves on pi-£e I9[a).. T.'ith the exce-: tion of the tost at 54 strolres T'or minute, the points fall ( uite miifcrmly on the curves. The error in this run is paohahly due to the inv-c curacy of the ven- turi meter, at Ic heads, this being the first run in -..hich the meter v;as used.
The curves show that the capacity ind horse pov/er increase directly v.ith the s^eed,
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For I VabJ'img ' ppiLDu
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ZO 30 40 So 60
SirtGLe :
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The efficiency ''nd duty increase v;ith the
s--eed, reaching- a aaxiiatun at ^bout ICC strokes
per minute. The general trenicf the curves
indic<^te tiiat, if the Tump cculd be o''--erated
at a STeed exceedln- ICO strokes per iiiinute,
there . ould be no increase in officioncj'' or
economy. It is also evident that tlie econ-
cnmj' increases greatly with the s'-eed. iTrom
the vvater r te curve, the steam consuinption at
4 strokes Tor minute is 284 pounds per I. h. I,
hour, at EC strokes it h.-.s already decreased
too to S64, .,hile at 40 strokes it is as low as
i*#. i*h-om there on, the decrease is com-
paratively slight reaching a minimum of i^
pounds at ICC strokes per minute.
The B. T. U. curve shov;s e:c- ctly the same characteristics. At the slov/est speed — 4 strokes rer minute ~ IBCCC B. T. U. are supplied i->er delivered horse po er per minute. At 2C strokes t/.is has already
-£C-
decreased to 44CC, and at 4C strokes only
2CCC B. T. U. are required. At 100 strokes
the heat CGnsuia-~tion is only 24C0 B. T. U.
Thus it is seen that an increase of 20 rer
cent in speed at lov>- velocities increases the
economy ( 18CC-440C) _ 75.5 ^'^r cent, 1800
In conclusion, \.e may say that v.hen ©".'der- ating v.'ith saturated steam:
1. The ninimuin efficient sreed is 40 strokes for minute,
2. That the economy increases ".vith the s-eed.
3. That the caracity, duty, horse ]^ov.er , and ef ficio::cy increase v.ith the speed,
4. That the ma.:ciLium efficiency, au- ty and c Tiacity are oht-vir.ed at the rated speed of 100 strokes per minute,
-">! —
Tests '..itii SuTerheated Steam.
At tiie ccmi_cncei2ent of tiiese tests it v.as found th&t the dror in rrsssuro thru the super- heater was nearly 5C per cent of the ua:K:imuia steam rressure attain^hle . ith saturated tteam. In the former tests a maiK^^imura steam pressure, at the higher speed,?, of 80 omids ;c.uge could be obtained; \. ith steam thru the su;^erheater , at lov. degrees of superheat, the steam pressure dropped to 45 ;'0unds an.- the maximum attainable speed v.'is 36 strokes per minrLte. The s;'-eed throughout the.'^e tests was maintained approx- imately const- nt, at about 22 strokes per min- ute. The discharge pressure v.as ":ept con; tt.nt at 6C pounds per square inch. The tempera- ture of the superheated steam v.as 1 ept as nearly constant as possible throughout the run.
At lo'..' decrees of suT^erheat not much diffi- culty v,as encountered in keeping the de,~ree of su-erheat constant throu^ehout the run. ^t
-22-
high decrees of superheat there v.as a fluctu- ation of 5 or u derroes, nd noro tine v/as re- quired to attain even ti:is cor.Jltion, The adfustment of the steam governor h-^d to he mc--de \ ith mere c^re, as it "became much mors sensitive as the tem-erature range increased. The discharge valve likev.ise had to he watched m.re carefully as there was considorahle fluctu- ation in the rressure.
Temperatures of superheated steam "lere read every E minutes, the cveraje v^.lue heing recorded for the run. Cbservations of the steam and discharge pressures, suction head, and temperature of water were recorded every 10 minutes. The speed counter was read at the start and finish, individual indicator ce.rds were tfiken, as in the tests with saturated steam.
Discussion
From the results oct' ined, the curves, pa^^e
-ES-
;2-fi a) v/ere dravn. The delivored or Tumr horr.e pov/er is seen to have a fj-eneral de- crei.se durinr- the series of su-'crheated runs. This, hov;eVGr, cannot be attributed to tl:o increase of superheat, as tlie aeliverea horse pov er is e lunction or speea ox '-ump, length of stroke, and delivery head. Lut it is rrcb- ablj)- due tc tlie inability to l:eep the speed for the various runs exactly constant. The high and lo'.v roints seen tc cor:.'esrond '..ith the high and low speeds res ectively. There is lij:ev;ise a ccnstsnt decrease in the ji.ech: nical efficiency "v.ith increase in the degree of super- heat. This is probably on account of incresed friction due to the unequal ex^.-nsion of the piston and cylinder v."; lis. To obviate this, the cylinder ehould be l':g£ed to prevent so great a difference of tenijB rature botv/en the inner and outer walls. The v.ater rate and heat supplied, decrease quite rapidly v.ith an in- crease of superheat. The duty and thermodjrnamic
-24-
2 4 Co.}
AjLiMn-xna.
3^ 'h)
dJttHotm
MAR5H Steam Pump
B.T. U. Pen I.H.R/H
SUPPLfELD . P<^nD.H.P.M
THLRn. E.QUIV. ofWorkDohe./!
■liiiiiii'iy-^'-'^"— TaMta
^^^mEafflg3Effl^BBmilBB3ai'»"'"''»'MMiLiiiJjjjiLiJ.w»iii!i!^
Z^(i>)
AHMoona
RuMHiMG Log
TtftT OF
Marsh Stciam Pump.
AT
Varying Splelos
WITH
Saturated Stelam
IMDICATORS ^ATER TaBOR 8239 SPG.
Steam Tabor fez-ife^SPG.
Apr. 19. 1909
NoorRuN
SuCTiOM
H£AO IMS. M..6[ zs [,2.n| 25
Stm.Lbs. ^^ '^*'
.S-I2.S8 2 3 s.sa a4.s I4.J8 2 3.8 U.47 2
i4.J-|3 28l 23.»L.»6|24.s|5:oal2S.8 Ln 1 2-i.S I7.11I 2-^
7; 208 27a 333 38+ I '^'♦S
Stroke
VE.MTURI
meter
IBB^^gBlimiBBBgBgBaBaBE3BBBB
miuidl
tWIBEHll
6.44 9.3 19.35 23.ia I 1 9. 1 1
RursMiiNG Log
TE.ST OF
Marsh Steam Purop
AT
COM*>TANT SpEE.D
WITH
SUPEIRHELATELD StLAM
Indicators ^ater T-abor 5TEAn Tasor
Kjjtti^gi ebEEESI kSeHSj t-fifUM Bsaaoi b^^^
MB
. I9M3I \s.oo\z9.y \t:et,\ 29. \
'3 34- I !S» jrj Vj37.^ly.oi- J( I l*\lf.r\ If,] 31. I ;3
3^«^ 4:»o J J SJ Jy. If:i4- J2. to Z0.S-1 tfc J/. ^3
EBlMaEffilEEiyffiKaigaBiaBngggagiiBHB^BBigzM
&0 I 60 6<» ^e
60 I &0
JPHBIBBBi
70 I 7«>
*« 64- U*^ \ (.3
60 \ \ SO
~~B9 BSBZi BBKZa BBSBH tSasa EZSBB BSBa ISQBJI ESDBS
5tm'!'l86. '^^ '^^ »J^ /3fl. 1,7 \ 9S. 9Z 83.
Punpto" 'o^T>- \iofoy faai \/o8/^\ 100S3 9073. ,04^4^ \ <)oio.
'3. |/a?i|5^9/V |g:fij-»-7fl.|ro°|907J |/ a*|t9ll- I-? "j) <7'-
ISSSEH33jCS!I
HflLgJ SBmxi PgflHHB IBHBtH HWF^CT BBBBTWi IHWngTH i
|BARoriW/5l2 9.2 4 I 29.4 I Z?> lz?.9S I Z*.4- I 2«t98 | 2f.y I Z<^.A-
. DOUBLE.
^-;» /'o',)
AHMOtJB
AVERAGE DATA
INDICAToH""cARD5 TE5TofMAR5H^TEAMPUMP
»l=»H»»,-^J^«'^^wirirJsll^LeI33an
NUMBER of RUN / ?\
STROKES PER MINUTE \\3.96 \/S.6J\Z9.20\4l.73 \SJ.9J \70.30 I 8fc.73]/oaIIl
QUAUJy of STEI\M (%) m.i4\98.0S [9 7. 7 J \^8.I0 \978S\9e.Z0\9S.lb 198 70 \
I \AREA ohCARD (Sq.in) II /.e/ I /./6 ±^99 \ hzo \/.zf \/.36 \ 1.4.9 \i.si I
jjiigMi^^^aiga|Bza^giHaHaBa
LEN&TH ofSTROICE (P
/IREA ofC/^RD C«/«N/f LEN&TH ofC/»ffP
LEN&TH -/STROKE
/»REAofC/IRO
HE/>D t-EN&TH .f CARD LEN&TH o^5Tff0h'£
LAREA*/ CARD
jCffANKl LENGTH ofg/lRD
LEN6TH ofSTROKE
\2.78\3.03 \2.9b 2.9J 3.i7/ IJ./Z \3.IU
imEamnrnm^i'iiiMMAWcmwanmrn
\L97\Z.I5 \Z.I4 \Z.II \Z.Z3 \Z.S-I \ZC7 \2.83
\ZA3 \Z.9Z 1 2.8* \2.67 \2.94 \j.08 \3./S \3./i,
.61 3 \ .903\ .68S\ 1
\l.79 \2.li, \Z.I7 \Z.lO \Z.ZS- \z.sj Iz.i^f \2.8S
\Z.^I \Z.9Z \Z.95 \Z.86 \ 2.9 7 \3.0S \j./J- Is./f
NUMBER of RUN
STROKES PER MINUTE
DEC-REE of SUPERHEAT
\ AREA of CARD
HEAD LEN&TH tf CARO
< 5 I LENGTH ./stroke:
/JREfl cf CARD
• \CFANK\LeH6rH ofCARD
LEMGTK ct STROKE
\AR£A of CARD
,r- \HEAD LENGTH of CARD
LENGTH ,fSTROK
AREA of CARD
■■ |CR/>NK[LEMGTH ef STROKE
I I LENGTH ef STROKE
kJijJdtiiH^idfm^nwtzi
izz.se\zz.i7\zi.4j\z!r.07 \z1.93 Izo.solzz.mznJl
_0___33^_72^90J_lZ9jd_![8j^lZ0^24±l_ JM_U^3_JJ;4^JJ8_U^_l2a±UZ^_/^093_ 2.9/ 1.9S Z.9S ^.83 Z9Z 2.94S 2.8*3 2.753
II tm-.9U I -9/1 I .614\ .904\ .969\ .ee^l .flAoi
\\I.I3\1.0S \I.I7 \U0. \I.ID l/./V M.et \/«9 I
\\Z-9I \Z.93 \Z.93 \Z.84 \Z.9t \Z9c^^\Z.e7 Iz.B^a
^snmEaimLEkmmMmnAw^kmmzmKwrnkA
Z.OB Z.ll p.04 \z.oo \Z.io \z.07 \2.0A \/.9<fJ Z.87Z Z.9I Z.90S Z.7J- 2.693 2.6 S z.ei3 2.748
iRHimi;iMmiif*Mmii'amrn!nmnTmwm-n?\m=ai\i
2,0j_^gg 2.04- 198 2.0 3 Z.o03\z.O3 \/.9ej\ Z.8i Z9Z 2.895 2.74 Z.073 Z.&Ai Z837 \Z.7Ss\
\Se3\ .9ci\ .995\ .esz\ .867] .8781 -87^1 .0So\
2 ^ ( e;
AJ.-UJ ■' • ■..' li
efficiency inciep-se almost directly vita the degree of superheat.
Thst f reater econoff.y is obtitined with an
increese in the decree of sui^'erheat, iLey be
seen f^om the follov.ing table. 5trrtin£- v.ith
saturated steam, or zero derrees of superheat,
the ;:ain in xer cont of L.T.U. £u;^rlied ot zero
decrees superheat is — see curve ij.T.U, per 13. H.
E. per ninute — , noted in following table:
Ser-ree SufB rheat Gain in Per Cent
75 11 ( 56CC-51CC)- .n
SGCC 100 14 ---( S6CG-51CC) - .14,
S6C0 150 21 (S6CC-£85C) _ £i
56CC EOO Z4 ---[ZGCC-275C) _ .24.
36CC E40 SS - — (26CC-24CC) _ .55.
36CC
The water rate at 0° it £CC pounds per I. H. i, hour. Ihe decrease in the '.vy.ter r;,te can be seen below:
Jea-ree Superheat Iiry Steam per I.K.I-. Hr.
C ECC.
75 159.
ICC 148.
15C 150.
2CC 118.
240 lie.
-E5-
Conclusion
The results of tiiis test v.culd inaic.jte that with the rump operating at constant s^eed,
1. The economy is a direct fimcticn of the degree of superheat.
2. That v.ith the rump in its present condition the mechanic 1 efficiency decreases . ith an in- crease in the do:;-ree of sur-rhet.
3. That the thermodynamic efficiency increases v.ith the degree of su-^erheat.
From this it dees not necessarily follov. that the economy of all pumps, nor even this pump, in actual use as a boiler feed, v culd be inc:^ eased by the use of superheated steam, as much v/culd depend upon the method employed in su-'-erheating the steam. V.hether or not the economy v.culd be increased v;hen jJhe cost of ;' reducing the siiperheat is considored, is beyond the scope of this ti.esis. This .ill depend entirel;^ upon existing conaiticns c;nd is a problem that must be left to the c^^ rating en&ineer to decide.
Resrect fully submitted.
Kay 25, 19 C9.
Part III. Bitliogrerliy*
Marsh I oiler Foed iTzinp. Engineering. 6C:946
Pumping Tests \.ith the Sujerheated Lteam U, S, Engineer
S7:140 Jno. 1, 'CC.
Pioinpinr iiJngine Test . ith Superheated Steam. Engineering.
70:221 ]5ec.l4,'CC.
Pumping -engine v.ith Superheated Steam. Sng. Heccrd
41:475 i:ay 19, 'CC.
»
PxuLping iiingine Tests v.ith Superheated Steam Pov.er
2C:£3 Dec. 'CC.
Conditions of Lax. iruxn-ing jingine 3fficiency. 3ng. i:ev;s
44:21E Sept.E7/CC,
Zl
Eoiler Feed-Ptunp Efficiency iingr. Londcn
8S:152 Feb. 5, '97.
Feed-pump Sfficiencies. Sleet. V. crld.
56:455 Se-t. 7, 'CI,
CoinpErative Steam Pump Tests with Satursited Steam. Sng. llev;s
51:3C1 Mar. 51/C4.
Tests of Small Steam Pump for Poiler Foed. Sng. r-.eccrd
44:E33 Sept. 7, 'CI.
Consumrtion of Steam Puinps.
iJH. Log. Lech. 'Ln^r. 17:145 - 95
Determining the Caj^acrity of a lov.er Pvunp. xov>er
Cct. 27, '99.
^e
Pules S; Fornml' s for Steam riun-^s jin£ r . — U . £ . L. - 56:49
Action of lUTips.
iJng'. iviag.
25:123
Some lump Problems. Am. i-acn. 22 :7V'
l^cli. 1,'99
Arr,
Feu. 2i,'y9
(Jom]"t:rative Value ci ^iixerent Arx?'ngenont of Air cliKmbers on iui.irs. Pov.er
21:11 Jan. »C1,
Setting the Valves on St asm iUiiirs, lov;er
17:4 Jan.
7 Fet.
7 L'y.)189 7,
7 Jne .
9 ilov.
a9
Po'..er 1.
Pov;er
18:19 Dec. 1898.
GelDhtrdt — Steam Power Plant iln ineering, p. 468
p. 475
Rogers — rumps S: Hydraulics.
J. C. Library 5£1.6
Q5CC
Economy Test of Peed-Iurps. linr-. — Lone en ~
87:4C Jan. 12, '99
:118 Feb. S,'99
:S45 Apr. 7, '00
3<^'
Apr end jy
Calculations
The follov;in£ series of c lcul--tions are for run nunbor 1 of the series of superheated tests ( only those hcinp- shov.Ti v.hich were deem- ed necessary for explanation) and are rrosented to show the i::ethods used in securin: the results which aprear on the y'intl Log of rage 2-41)). V/ith the exception of the determ 'nation of the quality of eterm at admission, thcS . coi.irutations show the methods for securing the results of our c.uturated runs also. Hence, the c^lcu- laticns for the cuc:lity of steam of the first saturated run are included in the follov/ing. In all esses, the dcta used, consists of the average corrected ohsei v^tions of the test un- der consideration. Peahody' s tahles were uced for heet vrlues.
Item 5. Single stroke per minute.
Speed ccunter reading at start, 3857.5 ST^eed ccunter readinr at finish, 419C.
(419C-g857.5) X 2 = L£.1V sinrle stroL-es 30 per lain.
Item 4. Lenrth of strolre
Av. lar- th of lioad end cards of water
cyl. = 2.91"
291 X ^^-^^ - 8.99' .
12 Av. len-th. of eranl: end c-rds of v.c.ter
cyl. = 2.92"
2.92 X ^-^i^ = '^^Cl'
(9C1+ 899) -T 2 = 9CC' . 3.7C4 = stroke ratio)
Item 5. larometer
B'crometer read 29. 4C" Kg.
2940 X .491 = 4.44 l^bs. rer so. in.
Item 12. Temperature of saturated steam se- cured from ste; m table.
Item 1* Degrees burerheat. Ifem 12 — Item 12
Item 18. Liechj^rge j.ressu:,e (feet cf v.ater)
60 ^ 1^4 _ 138.7 62.51 '
(62. SI = denL:ity of vt^ter at 7C®^
Item 25. Steam r-^:* !• H« ^« licur 5C6 4 1.584 = .01484
Item 51. Specific Heat of superheater steam secured from curves on -^e-ge 157 in ProfesEor uebhardt's "Stes.m i'o'.ver I lent iiingineering."
Item 55. Cu. Ft. of v.ater punped
1C5C7 _
62.51 " 165.5
Item 54. Gallons of v.ater puiiiped 165.5 z 1728 - 12S3 251
Item 4C. Plunger diepiacement per hr. (cu.ft A X L X U X 6C
A = Av. piston area in sc . ft. L = Lenrth of stroke in ft.
U = Sinrle Etrol:es f-er ciin.
i^^25 s 9 X ££.17 X 6C = S35. 144
Iterc_41.
Per Cent slip
Item 40 - Item S6 Item 4C
S35-3S1 - 4 _ 1.195:
io
335 3S5
Item 46. I. H. i-. (steam) PLiJI
33CC0
( .911z:9C5)( 115. 1^-111.6) ££.17
£3.3 X 3.704 £ £ -1£84
S3CCC X 1£ X 144
Item 47. I. H, P. (water)
59,6 X .9 X4035 x££.17 = 1.450 33CCC X 144
Item 48. D. H. P.
14C.8 X £0614., 1.458. 53000 X 60
Item 49. i<'riction bet'.een cylinders l,.).
I. E. ^. (steam) -I. H. P. ('..ater) - 1 , .:. P. ( steam)
1.584 - 1.458 _ 7 05 i.5B4
Item 50. Heoh. 3ff. = icO — 795 = 9£.05/u.
Item 51. Ji. T. I'. Surplied per hour SC6 (H4Cp S - qg) 306 [1167+1 .58) (5^.) - 2114 52] SC6 11C07.) = 5C8,CC0.
Item 52. B. T. U. per i. H. i- . min.
308, COO * 60 4-1.534 = 5240.
Item 55. Duty per million E. T. U.
140.8 X 2C614. icOCCCC = 9,4lC,CCC ft. l"bs, 308,000
Item 56. Termal 2qulv, cf v.orl: done rer hour. 1.468 X 2545 = 5740
Item 57. lEhermodynamic Efficiency.
5'?'40 X ICO = 1.213^^ 30 8, ceo -L-'=-L«^/»
Quality of ate am s:i ri+qi = rgtCp ( ts - t2) ( Subscripts 1 correspond to conditions in tlie stesm pi~e snd subscripts £, to those in the calorimeter.)
p. - 46. 9S Its. Abs.
tg - terarorature cf suTGrkeated steam
at atmospheric rressure of 14.45 lbs.
C-p = s-'-ecific heat of su-peilie- ted steum
in calorimeter. Its vr^^lue v;es secured
from curves on p^-Ce 137 of Professor
uebhardt's "Ste::m lower Pl'.nt iin.rineerine."
il = (9E0.2) 245.6 = 1146.3 .611 216 .-£11.1)
il = 1146.5 o. - £45.6 - g8.24>j. 920.2
1 ^ 1^ «| € ^ i i i^ At.
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