RATIONAL DESIGN OF STEAM HEADERS AND PIPING SYSTEMS BY FRANK MACKNET VAN DEVENTER B. S. University of Illinois, 1917 THESIS Submitted in Partial Fulfillment of the Requirements for the Degree of MECHANICAL ENGINEER IN THE GRADUATE SCHOOL OF THE UNIVERSITY OF ILLINOIS 1922 Digitized by the Internet Archive in 2017 with funding from University of Illinois Urbana-Champaign Alternates https://archive.org/details/rationaldesignofOOvand Pa^e I RATIONAL DESISU OF STEAi: KEAPERS ACT PIPING SYSTEIS. TABLE OF 00I!TE1:TS. Page 1 - Scope and Foreword. ---------------------- i 2 - Review and Criticism of I’ethods Usually Pollo\7ed in the Selection of Insulation. ------------------ 1 3 - Proposed Rational I'ethod for the Selection of Insulation. - - - 2 4 - Cost Factors Involved in the Selection of Insulation.” ----- 2 5 - Graphic Method of Comparirig Insulation Charges. - -- -- -- - 3 6 - Fethods Recommended hy Designers and Text Book V7r iters for the Proper Pipe Size Determination. ------------ 3 7 - Proposed Rational I'ethod for Selecting Pipe Sizes. - -- -- -- 4 8 - Cost Factors Involved in the Selection of Pipe Sizes. ----- 4 9 - Graphic I.ethod of Comparing Pipe Size Data. - -- -- -- -- - 4 APPENDIX I. DESIGK OF A SIITLE STEAI.' HEADER. 10 - Description. ------------------------- 6 11 “ Steam Conditions. ----------------------- 6 12 - Load Conditions. ------------------------ 6 13 - Steam Requirements. ----------------------- 6 14 - Selection of Insulation. -------------------- 8 15 - Analysis of Costs. ---------------------- 8 16 - Explanation of Items in Table Lo. l. -------------- 8 17 - Conclusions on Insulation. ------------------ 12 18 - Selection of Header Size. ------------------- 12 19 - Explanation of Itemis in Table ho. 2. - -- -- -- -- -- -- 12 20 - Conclusions on Header Size. ------------------ 16 APPEKDIX II. DESIGN OF A COITLICATED STEAI: HEADER. 21 - Description. -------------------------- 18 22 - Selection of Insulation. ------------------- 18 23 - Load Conditions. ------------------------ 18 24 - Steam Requirements. ---------------------- 18 25 - Provision for Future Extension. ---------------- 20 26 - Selection of Header Size. ------------------- 20 27 - Explanation of Items in Table No, 3. -------------- 20 28 - Conclusions on Header Size, ------------------ 26 29 - Closing Discussion of the Rational I'ethod. - -- -- -- -- -- 26 APPEIH)IX III. RADIATION LOSSES Ft^OF BARE AND IFSTJLATED PIPES. 28 . ►.yn^ T^/n I ,;j ; i i y ii tff-r . was* T ^'^.*-n V^-'- ■ ■' , . v- , ^ •■-T^— iSlt' .’i^ ^ , '^'i' " 1-,' ’•■•' ; '^^.. ■■■• ' ■ ■'' '4' -viA : ' ' ■ r .4 . . 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(Simple Header). ------------------- 13 3 - Determination of Economical Header Size, (Complicated Header). ---------------- 2I 4 “ Pressure Loss Analysis, ----------------- 34 5 - Hadiation Loss from Bare Pipe. -------------- £9 6 - Efficiency of Asbesto-Sponge-Pelted Sectional Insulation. ---------------- 30 7 - List Prices of Pipe Covering, -------------- 33 8 - Factor ”F’ for the Modified Babcock Pormula. ------- 34 LIST OF FICURES. 1 - Layout of a Simple Steami Header. - -- -- -- -- -- - 7 2 - Graphic Study of Insulation Thickness, ---------- 11 3 - Graphic Study of Header Size Determination, ( S imple Header 14 4 - Layout of a Complicated Steam Header, ---------- 19 5 - Graphic Study of Header Size Detemlnation, (Complicated Header). ---------------- 22 6 - Graphic Steami Plow Chart, - -- -- -- -- -- -- -- - 37 COHCLUSIOHS. Conclusions on Insulation, ---------------- 13 Conclusions on Header Size, (Simiple Layout)." ------ ^6 Conclusions on Header Size. (Complicated Layout)." - - - - 35 Closing Discussion of the Rational Method, """"""""26 Pa'^ 1 RATIOEAL DESIGK OF STEAi: HEADERS m) PIPING STSTEKS 1 - SCOPE AKD FOREWORD . The scope of this thesis is limited to that part of design which deals with (a) the selection of heat insulating coverings, and (b) the proper pipe sizes. The remaining two points to be considered in the design of a steam header, name- ly, the location of the pipe, and provision for expansion, are thoroughly treat- ed in text books and will not be considered herein. It would seem at the outset that the logical order of treatment would be to first lay out the piping scheme and determine the proper sizes. Having done so, the last item, would be to determine the thickness of insulation to use on the pipe. Under the "rational” method of design, however, the reverse order becomes better suited to the solution. The determination of pipe size involves the amount of heat radiated from the system, which in turn, involves the thick- ness of insulation. Further, it is good practice to set up an "insulation schedule" which indicates the economical thickness of insulation for all sizes of pipe which may occur in the whole plant. By drawing up this schedule first, the proper thicknesses of insulation will be known for the several pipe sizes considered in the calculations for the economical pipe size, 2 - REVIEW AM) CRITICISE OP MITEODS USUALLY FOLLOWED IE THE selegtioe of IESULATION. Conversation upon the subject has indicated the surprising prevalence of the idea among designers that "a little insulation does some good, and the more the better", or, as one designer stated, "Modern plants use extreme tempera- tures and the radiation losses become enormous; consequently, too much insula- tion cannot be used" . The fallaqy of this idea lies in the fact that the heat saved is not direct- ly proportional to the thickness of the insulation. One inch of insulation under average conditions saves about 89 per cent, of the heat, which would be lost from the bare pipe. Three inches saves about 94 per cent, of the bare pipe loss; so it is seen that the last two inches of insulation, which costs about two times as much as the first inch, is only 5,6 per cent, as effective in saving heat. The Magnesia Association of America publishes four charts, based upon four values of steam cost, each chart indicating the proper thickness of 65% magne- sia to use for each pipe size and for various temperature differences. The steam costs represented by the four charts are:- 20^, 40^, 60^, and 80^ per million Btu. When steam costs do not coincide with one of these four values, the result must be obtained by observing the two charts for lesser and greater steam costs, and approximating the intermediate value. This method does not permit of a satisfactorily definite solution. A more important criticism of these charts, is the fact that the curves are regular curves without inflec- tions. In the rational method of analysis it will be found that these cuirves are not regular, due to the fact that the list prices for various thicknesses do not follow a general curve. Hence the accuracy of such charts is to be doubted. 'j-v»i .t; : ^>1 I'.r' \^.;f *. Sw. , :•. l ! .■ v; "lo *: i" M,,;, (.; ;.? ;\>c .'I %■ ,i .-^ ■■-.* '/.i I >' 1 :-'^.,. R.i';i '0'!^ W I, jjiV .'Jil L.f'Oj ’ '••r ' 'ji ■ c-:r. -i .; v- i'ii" isle fc.?*?- IV tC- •’ “ - ‘’r ■ ' ■■ -ifr' •'• ■ f< < ’v;.' '’-^ .i-'^'- •;■ V’ l;'.'>r- V-' * 3 "*." ■ »'■ .' .'' •'. ’Sifu' ft? ■ -'^ J ': .'.-rT ft-*: 'Jrv « x . 1:7 ’■sri;^ ' X "J I j/v J l , r * -n.-.y ■•rr* 7 » . . - ^ »>• 1 ; j} ^ ^..•: y^- ■: ,v ' . . • • ■*■■■■ .' i,' , I* A 1 , 01 ' :.tf.- a"' ‘ . . .■ iu i -h'. \ ' Cv.’;- X j ', ' ';,'r ' . 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"ry. *• < V'. ■'! • - lit' ..i^ . v?' ■' ^ * *■ .^; f' ■'' '■ . : 5 ^' .,, , : ' . , ; , • V . ■ -ki^- 0 ; z .• '■ 'tl ’’ "’ ■ ^ \ 'i^'/!.y\ i : f v__ ■« u 'i- -I I ' •■'^ * y IV *.. ’’ jlifcJ'i, 1N^ ■* “ ■ .k_^- tyv3 ttft f li? .CO tyfl-Tl'C, XiCvl/m *l\i. it, A' V!]f€ 11^4 fi,: %^ T ol#fcfjtvr4 '^-■XX- • ' '.. ‘ ‘ . . . I'ii:.,# i^AAt , ■ ’ V. jklA# , r m xi m- Page 3 for some materials than for others, and increases somewhat with thick- ness, 5 - SriAPHIC R:ETH0D of GOITARIKS IKSULATIOK GPJ.RGEg. The manipulation of aata for the preceding outline is best effected by a tabular arrangement, but the results, costs, are most easily coir:pared and analysed by a graphic presentation. Since thickness is the argument, it is plotted as abscissa. Ordinates are costs, and three cost curves may be plotted for each pipe size; ll) Annual fixed charges on insulation, (2) Annual cost of heat radiated, (3) Total annual cost. The minimum value of the total cost curve is the criterion for the economical thickness of covering. If peculiar inflections occur in the total cost curve, the source may be discovered by a glance at the two component curves , 6 - l-ETHODS REGOM'EKDED BY DESIGNERS AEP TEXT BOOK WRITERS FOR PROPER PIPE SIZE BETERFIMTIOK Two general methods of selecting pipe sizes have been in comm^on use, namely, the velocity method, and the pressure loss method. The velocity method consists in selecting pipe of such size that the velocity of the steam will not exceed certain values. Undoubtedly this rule is based upon the theory that velocities exceeding the prescribed values would result in excessive pressure loss and consequent poor economy. This theory is only partially borne out in practice. Pressure loss varies as the square of the velocity, when the v/eight of steam flowing is the variable, and it is found that for velocities mnach in excess of 10,000 feet per miinute that the pressure loss per 100 feet of pipe becomes so great that it is excessive for long runs of pipe. But the average steam header layout is of such design that numerous branch connections, at which steam is fed into or bleu out of the header, effect frequent changes of velocity, such that one or m.ore sections of the header may contain steam at almost zero velocity, while another section may carry steam at an extremely high velocity. It would not be proper to increase the size of the section which carries high velocity steam*, because it is possible that a shifting of the load, by re- placing one or more of the operating boilers by others which have not been in operation, may almost reverse the values of velocity in the two critical sections mientioned. For this reason, it is aavisable in n.ost cases to con- struct the entire heaaer of one size of pipe, and it is seen that if the size were so selected that the maximum velocity in any section is less than 10,000 feet per minute, then the velocities in all the other sections woula be too lov/, due to oversize pipe, resulting in excessive superheat loss, or condensa- tion, and capital charges. Further, the velocity which corresponds to the miaximum efficiency in one case may be very aifferent from that in another case. For instance, the relative location of boilers and prim.e movers, as ”back to back**, ’’end to end'*. ^ ^ ^iii; p 3«: ir»> iii ar^ ^ ^ l H . ^^: i^j^li g ^ " |^^lH• .Tv-i-U- ^^i>,*i;:«,'*jet?y.-- ;;’-'.W-4*>.’>,i;^ ■ A,'," ^'i ' " , *<■. .'t^ •> s'f''.i‘Vi' ' '* ' ^ »i ■'fn. ^■. • ( .J ' '(’xf ; 'T/- , ■;; y/ 3 ^ ^ 1 ^- *» ' ■'" ' 16 *^'' -ft “t ^ J k •/, • I :'■ . ■>, .i’Teor its;,-d i- i — , . , ■ • .. ■• : • ‘VfS ■ ' •• ‘‘W**" -I K-' vvA, -f?fe^( ' ^^':'':-'A*'A. fv’ '! 1 '*:' 'i' ■■ • *?.•• • "' '.->^>- V'/ y.^,.;- ' . ►' Kv- ' >3 r * l|■■I'^' ''••‘i ;px(y^>?r:T. v:giy;- ia^ \ . . ^ |' I ' ,-^,?V'tior.n>iif., jri a»i»U , if'" j \<3 i«l ^ : I' •J“Af^''_Oi, ' t ',- "'X^Si^ ^.- ij .. ‘C^OX pt ,.?• b /Jtf. v'i'^ inAiWtf'V ’ * 1,1^9 « fs-y.r # I,/ ^vw»v 7 ’ MM ^ ivf /vv ^^4 v , , 'iJ tooX 'v ?;^r«i''.iP( ^iS^fe «4.<'X,iw ’itr- i^«»i dViwf ‘«naiBW§''‘V^’' *'iAXiCKf ''Vs f "'i.^^i'it:, Jfiir*, I^W’ i:>' . a«^^' I* l'> Wv#. 'f «r t j . 4 m aA . H ‘■at .i'rj Page 4 etc, has a decided effect upon the characteristics of the systea, and upon the velocity v/hich corresponds to Ciaxijrum econony. The pressure loss method consists in selecting pipe of such size that the pressure loss in the system v/ill not exceed certain values. The principal difficulty in applying this method is in knowing v/hat pressure loss corresponds to maximum economy. Different designers recommend from five to 20 pounds, and occasionally the theory is advanced that a loss of 50 pounds or more is not objectionable, since the energy remains in the steam as additional super- heat, The latter recomn.enaation of course is based upon a miis interpretation of fact, because although the expansion is practically a constant- total-heat process, the entropy increases during the expansion and the percentage of availability of the energy decreases, so that less is available for conversion in a prime mjover, and more nust be lost in the exhaust. It is impossible to assign a definite value for the velocity or pressure loss v/hich will correspond to maximum economy in ell cases, since there are so many factors, such as type of header laj^out, type of prime mover, station load factor, etc which affect the problem. 7 - PROPOSED HATIOFAL J^THOr FOR SELFTTIKG PIPE SIZES. ’’Rational J'ethod”, as previously explained, irc’icates that method v;hich effects the lowest total financial charges against the system; under considera- tion. The rational method of determining economical pipe size, then, consists in analysing the costs against the system with various sizes of pipe, and find- ing the size which corresponds to the minimum: value of total costs, 8 - GOST FACTORS mCLVED IK TEE SELECT I OK OF PIPE SIZE. The costs which are chargeable against the installation are: Fixed charges - Interest on cost of pipe, fittings, and insulation, erecteu. Depreciation of pipe and insulation. Repairs and maintenance. Taxes and insurance. Operating charges - Annual cost of steam to operate prine mover. Annual cost of heat radiated. 9 - SRAPHIQ 1:ETHCD OF GOlTARlIIg PIPE SIZE DATA. The compilation of data for the preceding outline is best effected by a tabular arrangement, but the variation of the several factors which affect the costs, as well as the costs themselves, are most easily comi>ared and analyzed by a graphic presentation. Since pipe size is the argument, it is plotted as abscissa. Ordinates represent oosts, velocities, etc, to suit the factors plotted. The following items may be shov/n to advantage: Steam velocity Pressure loss due to friction V ' i ’'im 'Vx:;. .,W--,^- • 41®**'- 'v; ;:;=, V.";'"’ , ’ '^ V rT^\ ‘ . '■* ■•’ ^- '■ '■'■/' ■ ^ ■ V*. T ' ■' ’f *' ■jCii.t'-ff'-M«:4 . ,*irrv:»t ir?»m - , ) t?»^ iifl .^-r^ ■'.t '*’)■ .) I • - ■f‘ 'v. -. A ’ r^' i) ?''f«^ »'t. . ^<:|.» «cjrX»V n r^S,. ' » 'aX J-^' ^ ' -’ ^/ ■, ■': ■ ^i<; -ts^ ■ '-^ , ®' .g -m -ga* • ^';, f-^..g >4 ,14 ,. . .' ‘fjf^ ‘V j!^ >>. .^ * i A^ ly ■. . . » -jZ' ]:>' ■"3 f ■ " ij' If » ®' ' '' T '{*'>11 '“;t.- ■‘«»^'‘“ i " «v .•V.(P. . '.?t. & .AQitifno , -y lSi>Xrtnai ,, ‘ - Page 5 Pressure loss due to velocity head. Total pressure loss. Water rate of prime mover. Annual cost of steam for prime mover. Annual fixed charges on pipe, fittings, and insulation. Annual cost of heat radiated. Total annual costs. . ;''-'->rt " m#' ^if \ I U*1 &'. .,; v<^ ’ -.: ■ . ‘1 'f P! ^i''‘ .?'i ) i%.; ' \ r ■ .. ' :C:- m '■ ’ ■^' ■ !'^H''?i->:- 4;':H:':: ■: ■ -.''iE; ■.(.■"<»i® ' -fl ■ hymk ■ vi'> ' ' ’ .vf /fSw 'iS j , ' ' - ,■'/' '^ • ^ Xf.r '•ii! ■ .‘i - -r w-'t - 1' i ,. ■■■ " ' ‘ ■ ^®’.--',:?. ■'/ w: . ' '^v .' ' - J itv. .^',^ ■' ’1, v ,"'. ■■^.-'o J k-:. |^v^::.<^ AiAfi A '"' ' ■' ■ ;fc'' ^ v' . ' * ■ ■*»«**“ *■■■'' SJL 4 7 .« ■ ■ , : ;■, ,, i»':ti kr; i'i-'f t ; .■ ■■^t t , ■ :■ ,: 'i5;jiv;, ^ .; w W' ,V' ^ :' ' r'.:., '. \: , • .'4 ^.‘t m X( APPELTIX I Page 6 App, I Design of a Siir.-ple Stean Header. The plant chosen for this example is Boiler Konse ”1” at Rational V/orks of Kational Tube Company at FcKeesport, Pennsylvania, This installation was completed and placed in operation in Fay 1919, 10 - DESCRIPTIOK. (SeePig. .1) The plant consists of one - 10,000 kw. (80^ power factor) Curtis turbo- generator served by two - 1471 horse power Babcock and V/ilcox cross-drum boilers. The plant is located in a space betv/een tv/o rolling mills, and since there is no rooir for future extension, additional capacity need not be provided for in the design of piping, etc. Also, since the steam conditions differ from those enployed in the general miill system, the plant may be treated as an isolated unit. 11 - ST£A^; COhDITIOhS, Eormal gage pressure at boiler drum - E50 lb, per sq, in. Konnal superheat - 150° P, TemiUerature of saturated steam - 406° P, Temperature of superheated steam - 556° P. Temperature of air (assumed) - 80® P, 12 - LOAD COPDITIOFS, The turbo-generator is intended prinarily to serve seven motor-generator and rotary converter sub-stations, distributed about the mill. It is also connected, through transformers and a high-tension transmission sj'stem, to other power generating and consuming equipment at plants of other subsidiary companies of the United States Steel Corporation, In designing the plant, it v/as anticipated that the normal load on the generator wox7ld be 8000 kv/. , and that this load v/ould be carried during 6400 hours per year. During the remaining 2360 hours, when the rolling miills etc, are not operating, pov;er may be received over the high tension system, from generating stations operating with blast furnace gas or waste heat as fuel. 13 - STEAl^ REOUIHFITETS. The water rate of the turbine at 8000 kw, output is 12,9 lb. per kv;h. with the steam conditions enumjerated. With the steam, required for auxiliaries taken from the end of the header farthest removed from, the turbine, the only load which need be considered in the design of the header proper is that required for the turbo-generator. At the design load, and under design conditions, the steam required for the turbine = 8000 x 12.9 = 103,200 lbs. per hr. * KSt’S' ' ' k o'kc^t :«J .. ■i'f) ■; ^4' ■'’ ■•'I'"'. 5' ■'■T'^^' •J'*.' » ,' - . 'T'- ■ ' ■ ' i »3 lM#v.”__i^'OS!^l: ' ■ ' ,««.•" ■ ■•.SO! ''''f'’l'- 'ST'^'i';'’.' r’ ^ .^\pf'\^' a>i5l“;ii«_‘^i’^:.a0ll£\ .JfPP. ;• -■'■'* Tn«*s5-*Jt3K''^-’5 - W.iT' ^ ^ u f *' < . . .-4tv-iV~/j.;f4' .-7, iw;i4>w jW'iK >vjvv;'v .. :*,t«p'«,. ~ ».-iA.ip , ji - vjir - ww,i* ;^v f ^ ii’"Vrk:#' ihtfiC'J . , ivc,*tn nd Jto^ v't . .Jj : ^ '.liv ^•■'. '■ ■ t ftT.T ■ .^'^V I? ,-!S; VT7.' ' 't' V'' V ‘ ‘ :!v> ■ ly- «*'>'• ■ s" rilaii', A\<'>. ■< ' ■‘‘..x/'j ^ ». ir ' 4 .... > _ ■ ' ’ ‘ ,•»(» ''• -V.v 1 . Vi'wl' ‘4if^ .l4*tot 'trSkt'-^i- ‘>>aJ i Y'*iJ fi?V' /■''^''' ■ ,^ ‘{pi- ,■ it dd^i^t ^ , l .« ' ....]^m ' ^." rn - ^-i-m i -iJi ^ |-,.. >y - ! ' .(iSf i.Vi .s,' ^ i* ■A^i Pa ;;j^ ■ ■4 f.', V:.'"- '■ ' ■ - ■ H:Vi^' v « '^ 1 . ..' j| v'^/^>'i.], ' .^ '^-['ji „* ’' ''’’^ ‘SUL \r^ hia ' .?■•*;* uX \ •*’ ' ,-pa*.iV ..5 ■'V &f S r ''!$<..k'' '* M ■ JM < ' .^a I . . • # rv '-M&M . r.- y '^1. \V^V'' 'vlfflBBIfe . .'t^'V., ' jjffl ••V"' ■ ‘ ■ i IWSf&V ^ ;%.i:/- i^;s:W!;,;,^ . C- " I 'iiriVf sUw f ' •'« X ;/W6i*4'>'- ? i,. . 1 , 41 '. , ■ “ ‘ ■ ■ 1 k .» .Vi ti.''^saij' .eit^i>..tw .' ■ ■'. .,' V-'Or-'"^' '' 4 <'«^ fc- u W . < > .ii {^ 3 .. Page 11 App« I Q T. < U. O o 52 < a: > CO UJ o CL ,< r o o UJ X c: 'v ✓ > u. o D liJ \- < o V- •< o q: o o h- < UJ r H THICKINE55 OF INSULATION. — Fig, 2.— Graphic Study of Insulation Thickme53. Pa^e 12 App. I s item 5 x 0,24, The fixed charges are assumed to be : interest 6^, depreciation 5^, repairs and maintenance 1^, taxes, insurance, etc, 3^, Total 15^, Item 7, Item 7 = item 4 + item 6, 17 - COKOLUSIOES OK IKSULATIGK. The curves or item 7 of the table indicate that 2 inches is the economical thickness for all sizes from 10-inch to 18-inch pipe inclusive, and that l-l/2 inches is the most economical for 8-inch pipe, Hov;ever, as the difference between l-l/2 inches and 2 inches on 8- inch pipe is only four mills x)er year per foot, it is considered preferable to sim.plify the specifica- tion by adopting 2 inches as the thickness for the six sizes of pipe considered. 18 - SELEGTION OF HEADER SIZE, Table Ko. 2 is the tabular solution of the header size determination. A comjplete set of explanatory notes follows the table. Pig, 3 is a graphic presentation of the im.portant items of the table. The curves are numbered to correspond v/ith the items they represent, 19 - EXPLOv^ATIOK OF ITEI’F ly TABLE W. 2, Item 1. From quotation submitted by Pittsburgh Valve Foundry and Construction Go. I'arch, 1922. Item 2, From quotation submitted by H. W. Johns -l^anvi lie Company dated February 17, 1922. Item 3, Item 3 - 0,15 (item 1 + item 2). The fixed charges are assumed to be: interest 6^, depreciation 5%, repairs and maintenance 1^, taxes, insurance, etc, 2%. Total 15^. Item 4, Cost of heat lost r length of heaaer (i, e. 202 ft.) x item 4, column 3 Table 1, Appendix I. Item 5, Use formula (2), Appendix IV. p = W2 L V F w = 103,200 4 60 = 1720 lb, per min. L r 165 ft. (from point midway betv;een boilers). ’’’y Vi*^i'' 't;„. ' •• :/ J.3 viigstt^iwaat.:, 'i',, , ' ' ' . ,.J^l •' ;J^ ‘ _ Y*' , ._ ■•' ' . 5 ’’‘i*, - . vl^' '-^ ’’■■ •■ ■ *K^L ' * ••‘■^SlWJk}**'*^ V ' J' ■ '■■ V‘ . ■ ^ - 4 . ■ i JSWl "J:* ita' ■. ' 1 ' . ■ ■ ■ ' ^!,j-«3r JOjk • ‘ :i;’ ^ i. ■ ■■■■«f»v _«, •■■* y' -■ JHWWgj - • w • o a) rH 'U trjc', c«^ r^rH ^ ■Tr.W:^ O'J c'/ o OrH O • • • oo 5: to rH pH ■CV t> O ^ ^C> • -cf • tvi r<; rH • • r<: r*.' "• r^: • o OJ (H X ^ H rH rH ^ Hi I'ja S o O pj t<.' t<*nr ' H< tv cv iH rH Pr ^ <1^ • (-1 • o rH ilj CM to ^ y-pi. r*J pH V! X O U j rH o » • • ctj o y^ UJ >“• H PH o> o o rrj tv iH • iS- • rH ^ O C't to tv • • C- t*. LM . . fH o> t*J <;M to O rH • r ' r a> lo (Th c- f*-’ o r<; o • • . X o ^ H rH PH £>• O C-- O rH H • r '•c-' X i;}* O' cv rH •fc rH 'O r'J O O fJ . r<.' O r*.' ^ ^ H t*.' -i}* o.; py iH fH PH PH cv r** fj O ^ •>^ X X a) PH tM O t\! Uj a; c- • > • rH Q rH ty r-l rH fv Hi o ^ 11}* ftj o°d X rH • • X tv tv to UJ • • . oa O t^j X yj X C'i rH •s rH vr UJ o O UJ ro . c<: OJ t*:! 1 1 iH r<; ptj tv cv i—i 1—1 pri -ej 1 o rH ty 2 O' ou g CO X X PH iH CH ^ 0> UJ rH • • • y-> tv O ■ rH X ^ rH ^ CV UJ O s . . 0^-0 tv • • o> o t'l X «> • • CM O X UJ t'< (H rH UJ r- o O i-v tv • UJ o p.' ^ ^ rH ^.' itr tv tv fH rH Tf.' rr.‘ UJ u ) •^’ a> to yj rH O ^ cja nj X X o O X c<: UJ (j^ 0> tv X fH tv iH r • . • • • • fi. •> -P'.-* CH to X O *1 rH X O Oa tv t*J H n (U iH rH f30 H f'l «0 X UJ H i:}' tr ■fH rH tv tv iH t\ C\( •v »— 1 f— ^ iH • • c o • C c • •M • c ^ • CD o © rr u •H c n c (U *rf C«| 65 ii ® t* o "2 ^ , 3 a • iS JZ «> S) u ♦> o c • • • js rL hH >.t5 .h c c O s> % 'O •H *» fM a> a ^ C 4) © C H 4) o • • 0 ^ ti -H 0 u ^ u. ti O' a 3 « CQ &H o Ph j , t) 02 5-1 'u.' a. C m »-« 'O N ^ Q • u* U 3 a> c •M Ih • tQ ♦» C lii a 4^ •H Cm 'O <0 M c u o CCI ® a ^ H O c a. c a o d y 'O €> O 9} 4^ t4 ^ iM H 4> ca XK) ^ 4-» • ‘j • • •H C M -M « « C c. H n >i Si c H ^ o c 3 g> o •H O -M «M #-i £2 >1-4 O ti r-t • Q> H • 0 • J3 jC 3 «4 rO (X H f— » H ^ ^ • C « a u 4> 4^ Q) ■H 1 0 c U (h 4> rr +> t. 9 ^ o CO c V| ' c o o u a to 3 C W H % ♦> C ^ Q ^ -H f-» ‘M C H H O H •H 4 n C Q. ^ .H 4 oca o o ^ ti 3 4» rH o •M -M ^ rC C a« 0 ) c fM .H C s: u 3 trf ® H _c2 •M iH V 09 3 4> 0 CO tr « o (M (D H C • H a 4> H O C! C *-4 O CO 4> o . "2 u cr m p M H O •H 'O 3 Ta CMC m c H O M 4> C C H 3 0) (b Vt M O H H C ® ^ 'S — 4^ C X » fH C c .c c u o 4^ 4) 9} 3 ca -C H .M O -H © © C 0 4> •P O c o H 5 «> tJ 3 ti Q. ® o o c doc Cm Cm U ♦> +> ou U •H SZ V Lt o O O r-. 1-1 3 O (D ‘H H • 3 ♦> j: c Jj to 'O ■a o o f-i J3 m ® n (i Lf d rH H H 3 3 •) -n •H O 0 CO «M a -H C O © 3 « Oj « c C C 0) > fc- a a ^ M S < H • u a (P !P •P ^ cv H UJ tc e- TO oa Q H « CO •< UJ ® c- M H H •H »H 4^ T-i tM 7^, o/ 0) r-i ^5 E-^ ."0 •H C 0) 4J (P W Page 13 App. I V r 2.20 F is obtained from col. 6, Table 8, Appendix lY. then: p r (1720)^ X 165 x 2.2 x P r 1.075 x 10® x P. Item 6. Page 15 App. I Prom "National Pipe Standards”, table p. 649, col, 3. Item 7. Area, sq. ft. ^ (item 6)^ Item 8. Velocity (ft. per min.) = 1720 X 2.2 - S764 area item 7 0.7854 , X = 0.00545 (item 6)^ 144 lb. steam per min. x sp. vol, area in sq. ft. Item 9. Velocity head, lb. ( ft, per min. 3600 X 2 X 32.2 x sp. Item 10. (ft. per sec.)^ per sq. in. z sp, vol, X 144 = ( item 8 vol. X 144 73,500,000 The pressure loss from saturated steam dnjm to header, including dry pipe, superheater, non-return valve, feeder, and all interrrediate fittings is 7 lb, per sq, in. (Prom test data on similar boiler, corrected to the proper rating) . Item 10 - item 5 + item 9+7. I tem 11. Item 11 - 250 - item 10. Item 12, Btu. per hr. «= length (202 ft.) x item 1* x (1 - 0,01 item 3* ) •Ool. 3, Table 1. Item 15. Total heat of steam at boiler nozzle (265 lb, per sq. in, abs. and 150° sux^erheat) = 1290.4 „ item 12 Total heat of steam at turbine nozzle z 1290.4 - - — lb. steam per hr. ■.- v-v^ I x a'^>.i ^ *i, -, 'i.'- I ■’'\'^4 ’ ' ', . - T* . .' : --w . • . m-y ■ " I « ,*V:, .ii' . ■• » . , •/ J 4 Pi' 'i' ' '■ -' ■ ' ■ .'.' 'P^''. '- . ■-■. .1(B:,1 ' '• ' ■»TDi' "I* ■''C* < ■ ■ . ^6.^:. ygy{)n^.^_ . -i t i ■ ' ‘V. ■ _ ' S *.# . ^ ;: M » • rr" ^ , * i * #*•* 4-1 ' ■■ . ^ ■ •” -*« -^' Ki iJ tiV-.: ,4 ,+,'..r/. ^ Mii ' 1. JH .. . , , . ;. , - mL., ym^^::::f m i(i '■■ " ■# '■ ' ■ ?v;' ■ ' J’m W' * “ . «^ ‘r'' ' ■ ,'■ "*< f>' ,'i- ■ ’. ‘ ' 5r« '^^‘1 '*' ’■' 'AvSmB . * N'ffriff' , i4':'f’''-'‘''fc-' o!^', r’Jtw;* M'K.'i'r ■’*'"'''’■18^^' .'■ '«^t'->"ffl>ir*'‘''^ '■' .te’ fe '.■.'* '■'■‘’■i ft'' i^'hi.'iA- ., ;v ivv.'’Tiy(^~ f-ii, ■ ,M' .1 a^/.' /• . •;■ . ■rV." '- • ‘•.‘^ »-..4' ' ? '^’V *'? I ICjv'ft, ' r ^ ^ ^ Jr “■'''* * * <* ^ • « ' I ' V , ^? - • " • Kt- ••'■ ^ '>.3 . j . H ... . I ’ r . & ^ k • j ■ A. irJL^ i ^A.'-' 7 ' If ^ ^ ^-ii •A 4 .ft ik *! >1 ‘ . .. m I I oif 'ft' 'iil ' iT '> V • I • ' _ I ' . 1 ' '■' # 4. ' ’ ■ • .l»',' *e'. ’ ■ I-, V:' , 7 .' "; ; l .^' |V- fe'W ir^t/'. ^iff.' ‘i’l wSs ‘ 'UVA ', '.S'; ■ tK- : -■-:•' '' "I'&y ''*27, S ' ' ■' f * -*-ifuu,< '..vtojii »/ .»f. 3 ^^ W'i ru^) 14 y™™®^ ’-' jj O:.-:. «'''( •*'< .'■ -^ A.. «l/:* nA » ». * f.^Cu^. 4X1*^^^ 1 - ‘n.» 4 J ,«■ 'IV J Xj- rS' ^.rwA I Pa{?e 17 App, I sizes are nearly counterbalanced by the advantage of less pressure loss. It is not to be concluded, however, that this condition occurs in all cases and that any size within a wide range will constitute an economical selection. (See conclusions at end of Appendix II). » 'Fv'-; '•4 ;,;;^a . — ■^™'b ' ^''^i #*:c. vv«^vii /&!r9i':^j;, jji»t> .wi>o*xlx Xaif5' I* _, ^ ' .V - .W;;. . '• ' ^ /( ii;:ft>«l>' . '-^ : ■rf 3 y,' . '. / ' :v ' . '• ■' -+ ,: ■ . 7 --^ ''sif' • .?• ■ _ . .. IL n ■* 1 . ‘ ' ./■s '. "i .f‘., . •■'■ I '4' - ’ 'i . " , !r/ * , '■i it; ■' * • '®SpK ^ .V r- ■ .'.. ■ V r'^,- .w.,'--. r , Vf ' •5sr ^ I ^ ;, ,)■»■. iltV »• •*''■ "• S':'^ I ijm •■'■fi V»f - ■ ' ■ ''i' '}.•: . «L>' '*■ ■, : '‘“ I 4'// ■jf*..-.,. , ■■ -r ■■' •\i| .. ' "' • iiSftiOTBit.'' V i ^'v ■ '.! '>' i* r ] ^■ If ,■7' ■•■i ,3: « I ' ' } ' I f cr » , ■•-i ‘'.?>aoi«r)' , riA >' ''^ ,,- '-•'- ' iiy ,. :Svi^.w«'i r V* ‘ ' ^ : f .wM «■ .■.■'"-#.;W®T.T£lTKTiS v?s:A' . 1 ^ Pa^e 18 App. II APPmiX II. DEE IGF OF A aOlTLICATED TTEAi: HPADER. 21 - DESGRIPTIOF. (See Fig. 4) The plant consists of four 15,000 kr;, (80^ power factor) tiirho-generators served by eight 1500 hp, "boilers, A 1500 kw. d. c. turho-generator , and a Kotor-generator set receiving power froir the main station generators, supply auxiliary power, the tv;o irachines providing a flexible link for the manipula- tion of exhaust steam to effect a station heat balance. One turbine driven feed pump and steam jet air exhausters receive steam from an auxiliary header located under the main header under the generator room.. 22 - SELECT lOF OF IFSULATIOF. The steam conditions are the same as in Appenuix I, and with the same coal cost, colorific value, and boiler efficiency, the insulation specification v;ill be the san,e, viz., 2-inches of Ashes to-Sponge-Fel tea for all sizes. (See par, heading #14ff,) 23 - LOAD GOIDITIOl.S. The anticipated loaa is an industrial load consisting of several steel miills connected electrically by a super-power system.. The normal design load is 45,000 kv/. during 6400 hours per year. 24 - STEAi: REOUIHEI'.'EhTS. The steam requirements for the plant (excluaing inteniiittent denands such as soot-blowers, ash dumps, etc.) under design load conditions are: Item EauiTanent a Fain generators 45,000 kw. @ 12.75 lb. b Auxiliarj' generator 1200 kw. C 30 lb. c Other steam auxiliaries Total Lb, steam, per hr. 573.750 36.000 20.000 629.750 The main generator load -would be normally carried on three machines, but as any one of the four might be off the line, it is assumed for design purposes that each machine carries one fourth the total load. Similarly, seven boilers would normally carry the load, but it is assumed that each carries one eighth of the total requirement. The actual steam distribution in the header system, would be different for each possible combination of units in service, and it is quite certain that the assumptions made closely represent average conditions. The steam required by each turbine = = 143,440 lb. per hr. 4 ^ssmi ,V I ■\,' -'• • " S'”’ -- ■■ llll^ ; • U I ■ f . * ‘ L. t ‘^ ’ L .*1^ j '.^ ■ ^ f. j* j . • . “ ^ »1 ?^r;'''‘vM .S' , ;.V ■ ■ *« w irio.oij VwiNt Unit, '^/''itSMtnf^^''^-:-^ w^V. ferv.;^ (I M -. ^ . t' l ’i u- to^f , ,1^ ■ ’, '.V * ’ ) . ' ■ ' ^ t-. " , .'■• ;:<„'if^'f-5^Jxwj«ir( n %aq - 1 ' '* I i._, • _ » ' .. 'S'-, -S'., , ■■ ‘ -.P' ■•’}J ' 7.Tf t: f. CU.' ol:^ # s, « «r'» r J ! ' .AsA/ ' ' !•“ i'VWBW?; ^ • I ^ ^ " '^ ' » ' : • -4 i>4* >■•«■>» ■ iM* ■ ■■ ' S', ' T- ■:‘j^ !r ' ' ( ■ *’■ ' <*■. ' , ,■.;. .•''V'' " , v/;j5iit.vc^>4W| ■ '^-v ’y ' It A ■■ ■ , ;■ ;r ,/ 1 ^,’S. WPl'«^/' . ■ V . ^ f ■•• ■ { • 'V ■» .'v<;--w.^>,^j| ■ ■'•:..a: 2. 42^^;:/' ;"v’'(,U;'.,. P- •’ '»;' P;. ; r>pift Page 19 App. II — Fi6. 4 — — Layout Of a Complicated 5team Header. Pa»e 20 App. II It is assumed that one-half of the 20,000 Ih, per hr. used by miscellaneous auxiliaries is taken from each end of the main header under the generator room. The steam distribution in the header is discussed under item 5, par. heading # 27 . 25 - PRCVISIOK FOR FUTURE EXTEITPIOK. The possibility of future extension must not be overlooked. In a layout like Figure 4, however, extension may be disregarded, since additional generators would be accompanied by additional boilers, and the piping would be extended with additional cross-branches, the system thus expanding similarly to the "Unit System", and each succeeding unit possessing characteristics similar to the original unit. 26 - SELECTION OF HEADER SIZE. Table l;o. 3 is the tabular solution of the header size problem, A com- plete set of explanatory notes follows the table. Fig, 5 is a graphic presentation of the important item.s of the table. The curves are numbered to correspona with the itemis they represent, A study of Fig. 5, (or Fig, 3) is enlightening. It is noted that curve 17 is a "U"-curve. Its components are curves 3, 4, and 16, Curves 3 and 4 are increasing functions, i. e. they increase as the pipe size increases, Hadiation increases because of the greater amount of surface exposea, and the fixed charges increase because of the higher cost of materials. Curve 16 is a de- creasing function because the v/ater rate of the generators (curve 15) decreases due to the lesser pressure loss in large pipes (curve 10). The sum of an in- creasing and a decreasing function always results in a "U" -curve, which must have a minimum value. The finding of this minimum value by analytical con- siderations is the basis of the "Rational" method of design, 27 - KXPLAI^ATIOK OF ITEi:S IP TABLE ITO, 5, Item 1, From quotation submitted by the Pittsburgh Valve Foundry and Con- struction Company, Farch, 1S22. (Correction made for header length). Item 2, From quotation submitted by H, W. Johns -Fanville Company, dated February 17, 1922, (Correction made for header length). Item 3, Itemj 3 - 0,15 (item 1 + item. 2), The fixed charges are asstuned to be: interest 6^, depreciation 5^, repairs and maintenance 1^, taxes, insurance, etc. 3^. Total 15^, Item 4, Cost of heat lost = length of header (i. e. 632 ft.) x item 4, colunn 3, Table 1, Appendix I. o o r-i CO e- 0) •r^ CD U d) n cO P p 3 o o 113 CO 113 (O CO 113 CJx tv; rM ea ■03 tv; tv. o P CO r<3 CM ■■■a ■03 o o O o o o 00 CM vcf cvt CM P -;/4 ea ■fa O >.'i O O O) '4j rM a) CT> •V O I-H iM ^-4 CD w O Oy U3 03 . C^ C<3 (.V . ■% " fM o 'o (.'( CO Ci 113 W 4? -Cir';* lA ■oa c W <^3 s § o -• o r<; o p o c- 03 113 o tv; rM •rr • • • cx; • 03 o r-l rH 113 o t'J o • o CO O P o U3 C^ P ^7> 113 . i.\i CV ii3 c6 -'4 oi • " c^ '13 CO o- C> 113 P ‘- • • 'P ^ rH ^ O •=r 2 y.' r- 'O 2 O (.V) U3 CO O P »o 2 ^ tv; 2 2 d o? ^ o 'd s • •H 4; 7) P o © CO 7) P o Oi •■0 o • © g © 'd UJ P X V c rP u C •H p • o • CO •ri •ri © © •ri Q) •iH Cm CO X) c P o c ■;n X © P p p Mi »ri Cm c • X • ri 0 I 4 rd P • o •rl cr X X 3 S •H rP p • CO ft Ut 43 P to P o c CO ti © d' p 0 r*< c o o 4> Qi 90 • (4 p -M c • •H Mi ■ri •H © Cm t4 d ^—4 (0 <0 Oi •M Oi 4^ 0 © 'o 43 P 4> P H © (3 H c (P c: c Oil e« X Cm 04 • © 4 •ri v« o (D O •H U o O {3 © © X •H x: c Ou © **< ri O ■P (4 p •ri u Oi • © * © 3 u (C 0 Cm o 4^ © c P P 0 ) O CO p O • -o U •ri © 0 Cm Q ■O 3 T3 CO Q p o 3 0 p (0 to ]> 4^ O 4 OS Cm © © • Cm d c:j 0 ) X 0 ) r-H 3 © X © rr Q P •H •H 0 •H © © C d P Cm o a> 'd >> >5 U © Q © X d d (0 'd o o Ut © rt rM u p P 3 3 CO •H •ri o 0 (0 © •fi 05 © fT to C a o ao rM rM p • © 'O P Ot P o c c u c C © © .0 X (4 d 0 3 o o < *< Cl Mi > t- ri a. {P W CO CO cv (<; cv C'.' o c\/ C\i p CO 00 o. r<3 cw o> r o> • cr> cv; CM 00 p . • ox '13 CO Tjv 01 t<; •» 113 OX * O ox P 03 113 CM P OX . o O ox P . a) 113 Ox CV( P C7> % CM rM 0 0 • 0 (-1 t<3 va* tv; CO • 0 rH 0 CO r— f rd a> 00 CC' C'l rd rd C'.' CM aj 03 rd CO CO o • CV- O! CM O f) U3 • O o o> fjx 113 CM I — 1 a. 3 tri U'.' tv; U3 rd l-t fS a; 0 •av « 00 03 CO CO rd 03 ■03 fO rP i-d o- rM CO £0 0 • 00 'X) CM 'O »M ■03 ■03 ox ^3 CM CO OX c^ ^ •» o P-' CO CO CO CO ■rr} ^ 3 •P 0 / P »■ iif: .t^k -.^V ^•" V' j'f,’’ A> ^V ' i^.' > ►V’l V • jLT r 'l ‘(i • .'(iSktrt'Mw'ffet-T.* ^ soIM i^^g ' ”lfil' K’ fe,.'-’' '■ ^ iRfcsJt'V '.’ * ‘--ir‘>;- ! swJaXoj^al -.; ®|p' ;''5f v-.i* 'til) fl«?aU^-a.It4ltfori fti' '^SK^r. > M‘1: : ' v-l* “<*< »■'. >. '■”. 5 *■■''■ -. , • - W. .;., ^1 'tils rJt9'i(?^iOf .;v. ;%■ r> ., ^■ ^ ^ r;:: V. v''U y :'^.' ' ■■ , y, ' ^ ■ . . ;\‘>^ m;'' ■ . " '1 -(‘<1 •...' yy^,,, h£ \'ll. t.. . . ... m_. Tafcle No, 4 Pressure Loss Analysis of Fig. For 14-Inch Header. Second Trial Pressure loss 00 809 *0 330 *T 2Vl *0 rf tv CV rH r-» 1—4 <-H O O d d d 0. 114 0. 240 0.010 + O ft o tv: O’: o O O O o o d O 03 o o o d P. 24 A. II -H • O o . * rl (U ts o o o to c- ^» o o to 00 tL; O f.' tv f<3 C43 .C*.' •>' •> pH i-t O O CV -tt O H' to ^ ^ ^ r t rH CV »— 4 tii U3 u; o f*.' C*.' to CO 00 » ^ ^ 00 uo 00 rH t ft 03 t<: iH ft 00 ^ 00 ^ ft? ^ 00 f— 1 CO v. CO iL. •H 'tf* pH go 00 a> odd a> *o tt/ o o rH O O d d d o> to to r- rH pH tv O o o o rj 1X3 rH CV o O O O d d o £> CO o t> o <-• d o >> •H d o • O r-i *■ O 'H f> 1 ft . o to Xi ft o o o CV tv t'i o> o» o> CT> o> o o o tv tv: CV o o o O *tit CV t>; cv: K ^ rH to to t*3 CV tv rH o o o O t\i 00 t\: ^ sf •> «k •K pH CT> to CtJ 0> LfJ rH iH o o o Jo ^ CO Oi -tr Ik ^ to O ® cv cv t—i o o 00 cv: tr o> Ik Ik to o> Ift 03 rH c; -M U) tu C 0) 0) ft ft w tv C<3 ^ O O rH ft rH prj t<3 ^ ^ 'T C<-' O 00 vji cQ tv: to to cv rH rH rH iM ^ C\i c: o •H 4-> y ';''''Vi‘:'; <‘. 1 , .' ■■■ ' .fTii . ' ' r ill ■ *J • ■ ,' ■■ ' '■ ' ■' . ' .' '■ ‘ is *3 !jrm . ' >■■ S ■'^ '£iltr!>n - / 'i ' ■ '-r^' ' '. • y,/.ivK|:j a :, •• •; . ’ Cr^ ; ' xJ ■ - - ■ ■•’ f .o:-: < *i J ' ‘ ^ ^ .* f r ^ * • ■ ■ ■ ' •^ J N- . 4 - ^ " , ;; .ii;.;- ■' : •' : • ' - ? "i r - ■ ' f- * I '.‘■^.n J' -r''’/ : 'y*'" ..'^xl ',.•}• !:It4Cv v'p' :>■■•) rjixr. & l fc " t (oOf ■•‘J r ::: -..'‘ 1 . '• ■ f .•'■.* '•1 * f ‘ ot.,'I.yr '?:^o: . 'Lr.'.'O U: ' . '!tf ''}o ';?-^':'tj •'■’'trryf’)'/ ■?/{•■ '■ Hiili nc'’ /;r '« l>, f r;.-.’c?fl:ooo •. :*. .,. ^ d-:- ‘t ■> '“r e v 6 \ ■ - ^ ’ it ’ oi ^ : , , . ,, nr> o :*■ ttS T- ^ ' ■«• \ J.urt 5 '-o, r,... . _ . J tv' .•'•'■■■. Uh' ■ *•;.. ■' ,' i' -"'I.'" '.'.v t**i’ cvt ; :} t .» r-v^ '■■ ’ - • .. tv ■ ^V'l <■ SrC f #■"* ‘ ■:!il :>:■ . ^ ,rp: ■> : ti • , iTj .* 2 %;.'. X'.'uTi ;irr H ‘T! : .H-M J'-aX - 4 ^ , X-.. prci n : OjV VyvlJAt 'V. v^ii; . . Efi*^ eek ; : 'C ••'4 ’'u v-xs . . ■• - f '.=C. .’’j i'.'' ;• ■c-.( nr>fif- f J.'ylj , -s i U'.’ .:**GC -Ti’ 'i. AX.' .■yu- = .-SXixv ,l.X-r ■■ ■• .;0 tl^'V , ..T : i X-*' ui«rfi ■I •- i Ix)";: .; o.t. ''■* '-x- , ‘ . ■ ' ', •' t ; >jrf ’"xio:' , ,r’ T. T ^ : ■‘.I • i.*- I iT<.' . ‘ a: ■' ( 7 C Ixfjil •..tr.-.L'l V'K x!V ':,^v^ • <;•,•» ’■, iV ' . ' t •■,■ ?PW' 2( ' .jS ■ V, ’ \ ■I V r. ..■ V: • . X ♦’■ VT*‘ ‘, ' , i‘' r *\\ A ■•:•.:* » ^ V ^- ' .u • *' *« A .. /v , ' ' \Aty^SaLlt^k • ri ' fir 4 .vrJvit ’r, ; ''iiti' ,•:■■ '"■ 'a.' .ff.Xv ' f .’j Page 20 App. Ill APPEKDIX III. HALIATIGIj LOSSES FEOF BARE APE lESULATED PIPES. Protably the most reliable experimental data available on radiation losses, are those reported by Ej:. L. B. Eclvlillan in Vol« 37 of Trans. A.S.E.E, Table Eo. 5, published in ” Johns-Eanville Service to Power Users” is based upon EcEillan' s experimental data, and is considered reliable. The tempera t\ire differences at the column headings in this table refer to those between outside pipe surface and surrounding air. Analysis of Ecllillan’s experiments indicates that with zero velocity inside the pipe, the inner surface and metal resistance for bare pipes is about 1.27 percent of the total resistance for saturated steam, and 9.45 percent for superheated steam. The magnitude of the inner surface resistance is known to decrease as velocity increases, but the exact relation between these two quantities is not known. It is known, however, from tests made with air, that a small increase in velocity is accompanied by a large decrease in surface resistance. It may therefore be concluded that at the customary high velocities in steam headers, the inner surface resistance is less than one or tv'O percent of the total resistance, and hence sufficient accuracy is obtained by neglecting the resistances imposed by the inner surface and the pipe metal. Table Eo. 5 may then be used by interpreting the column headings as "temperature difference between steam and surrounding air”. The efficiency of an insulating covering is defined as the ratio of the amount of heat saved by using the insulation, to the amount v/hich wou'ld be lost if the pipe were left bare, expressed as a percentage. To determine the amount of heat radiated from an insulated pipe, then, it is necessary to determine the amount radiated from a bare pipe, and multiply this loss by the efficiency of the insulation. The efficiencies of comrercial pipe insulating materials vary from about 50 percent to about 97 percent, depending upon the nature of the material, the thickness of the insulation, the temperature difference, and the pipe size. Table Ko. 6 taken from ” Johns-Manville Service to Pov/er Users” shows the ef- ficiencies of Johns -Eanvi lie "Asbesto-Sponge-Felted” insulation. Table Ko. 7, from " Johns-Eanville Service to Power Users” gives the list prices of all classes of pipe coverings. Discounts vary with the grade of material and market value. c^'^frtitrlryiiiti ^r. ■*;'t f. ^ r, A''- r:- y f ! s !V^''', ., ':» •■‘"i ■<■ V'- ■ ■■ s v ■ *. \ V. r. . 17 ', •,■ ■, "■ fj^'. • V..', '.'7,!f'. IS ' ■ n am k mKii mSiiSi &>! f: :-m ', .:j '.ASf^a ibSTi "m . #lJiif UvfiS 4^^. j:j^,rs?.»li*J«^ Mi- I 4 d.A-'' ’■. aftoat'-' la 'TC . f©^/. 'wi' r'tiRWiMril ,- .■4 . 5: . • i6«c«td^ •'ib ■ v ... ^7 • / • f -.j^rtuyi.ii^cn 'ni 'Vy*^' o'Mfc i'A '^4 ' ..I . ' Afc * ,;.. ■ 7. :;: •■•>&':• ■'■v-'*:^? ■ ia.j’S- I iEf^- f ,': '^iAi .i ‘.2 ''.ii'. - >.>^1 '■ •*• ‘ .v'ii'A '■' f' ' I A-'-.'E ''"“TvjKi&Mji - ■' ;:v-- :■ . ..v.v;..: 7 :j,;r, . » ' or- (■ ■ ^ Page 29 App. Ill TAPU ITO. 5. RADI AT TOP LOSg BARE PIPE. Total Heat Loss in B. t. u. Per Hour Per Lineal Foot of Bare Pipe of Different Sizes and Per Square Foot of Flat Surfaces and at Various Temperature Differences (For finding losses at temperatures between those shown, the B. t. u. Differences per Degree are given in small type between the Main Columns) Area of Temperature Differences Pipe Sur- 50° 100° 150° 200° 250° 300° 350° 400° 450° 500° Pipe Size lin. ft Heat Loss m B. t u. per lineal ft. per Hour K" .220 21.5 *.52 47.3 ♦.64 79.2 *.76 117.3 *.go 162.3 *1.06 215.2 ♦1.28 279.1 *1.52 355.1 *1.93 451.4 *2.37 569.8 H " .274 26.8 .64 59.0 .79 98.6 .96 146.8 1.11 202.1 1-33 268.5 I.S8 347.6 1.89 442.2 2.40 562.2 2.95 709.7 1" .344 33.6 .8i 74.0 1. 00 123.8 1. 19 183.4 I.4I 253.7 1.67 337.4 1.98 436.5 2.37 555.2 3-03 705.4 3-69 891. IK" .435 42.5 1. 01 93.6 1.26 156.6 1. 51 231.9 1.78 320.8 2.09 425.4 2. S3 551.9 3.00 702.1 3.80 892.6 4.68 1126.7 IK" .498 48.7 1. 17 107.2 1.44 179.3 1.72 265.4 2.04 367.3 2.39 487. 2.90 631.8 3-44 803.8 4-36 1021.9 5.36 1289.8 2" .622 60.9 1.46 133.9 1.80 223.9 2.15 331.5 2.S4 458.7 2.99 608.3 3-62 789.2 4.29 1003.9 5-45 1276.3 6.69 1611. 2K" .753 73.4 1.76 161.6 2.18 270.4 2.60 400.3 3-07 553.9 3.61 734.5 4-37 952.8 S.19 1212.1 6.58 1541.1 8.08 1945.1 3" .917 89.6 2.15 197.3 2.66 330.1 3-17 488.8 3-75 676.3 4.41 896.8 5-33 1163.4 6.33 1480. 8.03 1881.7 9.87 2375. 3K" 1.047 102.3 2.46 225.3 3.03 376.9 3.62 558.1 4.28 772.2 5.04 1024. 6.09 1328.4 7.23 1689.9 9.17 2148.4 II. 3 2711.7 4" 1.178 115.1 2.77 253.5 3-41 424.2 4.07 627.9 4.82 868.8 5.67 1152.1 6.85 1494.6 8.13 1901.3 10.3 2417.3 12.7 3051. 4K" 1.309 127.9 3-07 281.5 3.79 4 70.9 4-53 697.2 5-35 964.7 6.29 1279.2 7.61 1659.5 0.03 2111.1 11.05 2684. 14.1 3387.7 5" 1.456 142.2 3.42 313.1 4.21 523.8 5-03 775.5 5-95 1073. 7.00 1423. 8.46 1846. 10. 0 2348.4 12.7 2985.7 15.7 3768.5 6 " 1.734 169.4 4-05 371.9 S.04 623.9 6.00 923.7 7.09 1278.1 8.34 1694.9 10. 1 2198.7 12.0 2797.1 15-2 3556.2 18.6 4488.5 7 " 2.00 195.0 4.71 430.4 5. 79 720.0 6.92 1066.0 8.10 1475.6 9.61 1956. 11.66 2539. 13.78 3228. 17.46 4101. 21.6 5180. 8 " 2.257 220.6 5.30 485.7 6.54 812.5 7.81 1203. 9.23 1664.5 10.8 2207.3 I3-I 2863.6 IS.6 3642.8 19.8 4631.4 24-3 5845.6 9" 2.52 246.0 5.92 542. 7.30 907. 8.72 1343. 10.34 1860. 12. 1 2465. 14-7 3200. 17-4 4070. 22.0 5170. 27.2 6530. 10' 2.817 275.4 6.62 606.2 8.16 1014.1 9-75 1501.5 II. 5 2077.5 13.6 2755. 16.4 3574.1 19.5 4546.6 24.7 5780.5 30.3 7296. 11' 3.08 300. 7.26 663. 8.92 1109. 10.66 1642. 12.6 2272. 14.76 3010. 17.9 3905. 21.3 4972. 26.9 6315. 33.3 7980. 12" 3.34 326. 7.86 719. 9.68 1203. 11.54 1780. 13.7 2465. 16.02 3266. 19-4 4235. 23.1 5390. 29.2 6850. 36.0 8650. 14'o. d. 3.66 357. S-.SQ 786. 10.64 1318. 12.64 1950. 15-0 2700. 17.06 3580. 21.3 4645. 25-2 5905. 31.9 7500. 39.5 9475. 16"o. d. 4.19 408. 9.84 901. 12.2 1510. 14-5 2233. 17.2 3095. 20.1 4100. 24.4 5320. 28.9 6765. 36.5 8590. 45.2 10850. Flat, Heat Loss in B. t. u. per sq. ft. per Hour Curved. or \ . 97.5 : 2.3s 215.2 2.90 360.0 3.46 533.0 4.10 737.8 4.80 978.0 5.83 : 1269.4 6.89 1614.0 8.73 2050.6 10.8 2590.0 Cylindrical 1 Heat Loss in B. t. u. per sq. ft. per degree temperature difference per Hour Surfaces 1.950 2.152 2.400 2.665 2.951 3.260 3.627 4.035 4.557 5.180 ♦Example 2" Pipe, 235° Temp. Difference. 235° — 200° = 35°; 35° x 2.54 (B. t. u. per degree)=88.9 B. t. u. 331.5-h88.9 = 420.4; B. t. u. loss at 235° Temp, difference. TABLE rO. 6. EFFICIEKGY OF ASBESTO-SPOESE-FELTED SECTIOKAL lESULATIOL. Page 30 App. Ill EfRciencies of Standard Thick Johns-Manville Asbesto-Sponge Felted Sectional Pipe Insulation on Various Sizes of Pipes Temperature Difference Between Steam in Pipe and Air Surrounding Pipe Pipe Size, Inches H. M. IK. 1 K- 2 . 2K. 3 3K. 4 4K. 5 6 7 8 9 10 50° 100° 150° 200° 250° 300° 350° 400° 450° 500 Per Cent Efficiencies 68.5% 71.9 71.2% 74.3 73.3% 76.2 75.5% 78.1 77.1% 79.6 78.7% 81. 80.4% 82.6 81.9% 83.8 83.1% 85. 84.5% 86.2 74.3 76.5 78.2 79.9 81.3 82.6 84. 85.2 86.2 87.4 75.7 n.i 79.5 81. 82.3 83.5 84.9 86. 86.9 88. 77 79. 80.5 82. 83.2 84.4 85.7 86.7 87.6 88.6 78.6 80.4 81.9 83.3 84.4 85.5 86.7 87.6 88.5 89.3 79.8 81.5 82.9 84.3 85.3 86.3 87.5 88.4 89.2 90.3 80.6 82.2 83.6 84.9 85.9 86.8 87.9 88.8 89.6 90.3 81.2 82.8 84.1 85.4 86.3 87.3 88.3 89.2 89.9 90.6 81.8 83.3 84.5 85.8 86.7 87.6 88.7 89.5 90.2 90.9 82.1 83.6 84.8 86. 87. 87.9 88.9 89.7 90.4 91.1 82.3 83.8 85. 86.2 87.1 88. 89. 89.8 90.5 91.2 82.7 84.2 85.4 86.5 87.4 88.3 89.3 90.1 90.7 91.4 83. 84.5 85.6 86.8 87.6 88.5 89.5 90.2 90.9 91.6 83.4 84.8 85.9 87. 87.9 88.7 89.7 90.4 91.1 91.7 83.5 84.9 86. 87.2 88. 88.8 89.8 90.5 91.2 91.8 83.8 85.1 86.2 87.3 88.2 89. 89.9 90.6 91.3 91.9 Johns- Manville Asbesto-Sponge Felted Sectional Pipe Insulation on Various Sizes of Pipe Pipe Size, Inches K. 1 IK. IK- 2 2K 3 3H 4 4K 5 6 7 8 9 . 10 Temperature Difference Between Steam in Pipe and Air Surrounding Pipe 50° 100° 150° 200° 250° 300° 350° 400° 450° 500° Per Cent Efficiencies 85.2% 87. 70.3% 73.7 72.9% 75.9 75. % 77.7 76.8% 79.4 78.4% 80.9 80. % 82.4 81.5% 83.5 82.9% 84.9 84.2% 86. 76.1 78.1 79.8 81.3 82.7 84.1 85.1 86.3 87.3 88.1 77.8 79.7 81.2 82.5 83.8 85.1 86.1 87.2 88.2 89 79. 80.7 82.3 83.5 84.7 86. 86.9 88. 88.8 89.9 81. 82.7 84. 85.2 86.2 87.2 88.1 89.1 89.9 90.6 82.1 83.7 85.1 86.1 87. 88.1 88.8 89.8 90.5 91.1 83. 84.5 85.7 86.8 87.7 88.7 89.4 90.3 91. 91.6 83.6 85. 86.2 87.2 88.1 89.1 89.8 90.6 91.3 91.9 84.2 85.5 86.7 87.7 88.5 89.5 90.1 91. 96. 92.1 84.6 85.9 87.1 88. 88.8 89.8 90,4 91.2 91.8 92.3 85. 86.3 87.4 88.3 89.1 90. 90.6 91.4 91.2 92.5 85.4 86.7 87.8 88.6 89.4 90.3 90.9 91.7 92.2 92.7 83.9 87.1 88.1 89. 89.8 90.6 91.2 91.9 92.5 92.9 86.2 87.5 88.4 89.1 90. 90.8 91.4 92.1 92.7 93.1 86 4 87.7 88.6 89.3 90.1 90.9 91.5 92.2 92.8 93,2 86.6 87.8 88.8 89.6 90.3 91. 91.6 92.3 92.9 93.4 OS r tt i i U w i iiaAift W(ii»tfS‘^iiM|iig.i?» » ‘“W / i* r\ * I*'. .'. 'Jj/sk. -. • *'»»* ^ . r' Slir -isS : -. -f/' ' i' if ^ -■- ■*.Ct 4 ¥ {*;* ... -i ;• , ' ...'’'•'S^ * A.!'®' .■• ^V'.!r ’ Ik* ^ , ■ ', \*'' y. '..' '. ) '■■ "^V . '1 :. , - ’ . 2 ■■ ,, .■,-- '■ (jg^' Page 31 App . Ill TABLE KO. 6 - (CCKT’D) Efficiencies of 2" Thick Johns-Manville Asbesto-Sponge Felted Sectional Pipe Insulation on Various Sizes of Pipe Temperature Difference Between Steam in Pipe and Air Surrounding Pipe Pipe Size, Inches 50° 100° 150° 200° 250° 300° 350° 400° 450° 500° Per Cent Efficiencies 34 . . 73.2% 75.6% 77.5% 79.2% 80.7% 82. % 83.5% 84.6% 86.1% 87.4% ^ 76.5 78.6 80.3 81.8 83.1 84.2 85.5 86.5 87.8 88.8 r ‘ 78.8 80.7 82.2 83.6 84.8 85.8 87. 87.8 89. 90. 134 80.5 82. 83.6 84.9 86. 87.1 88. 88.8 89.8 90.8 iH 2 . . 81.7 83.4 84.7 85.9 86.9 87.8 88.7 89.5 90.4 91.2 83.6 85.1 86.2 87.2 88.1 89. 89.9 90.6 91.4 92.1 2H 3 84.3 86.1 87.2 88.2 89. 89.7 90.5 91.2 92. 92.7 85.6 86.8 87.9 88.8 89.6 90.3 91.1 91.7 92.5 93.2 SM 86.2 87.4 88.4 89.3 90.1 90.8 91.5 92.1 92.8 93.5 4 86.7 87.9 88.8 89.7 90.5 91.1 91.8 92.4 93.1 93.7 4 3^ .... 87.1 88.3 89.2 90. 90.7 91.3 92.1 92.6 93.3 93.9 5 ' “ 87.5 88.6 89.5 90.3 91. 91.6 92.3 92.8 93.5 94.1 6 88. 89.1 89.9 90.7 91.3 91.9 92.6 93.1 93.8 94.3 7 88.4 89.4 90.2 91. 91.6 92.2 92.8 93.3 94. 94.5 8 88.6 89.6 90.4 91.2 91.8 92.4 93. 93.4 94.1 94.6 9 88.9 89.9 90.6 91.4 92. 92.5 93.1 93.6 94.2 94.7 10 89.1 90.1 90.8 91.5 92.2 92.7 93.3 93.7 94.3 94.8 Efficiencies ©/■ 2 ^ " Thick Johns- Manville Asbesto-Sponge Felted Sectional Pipe Insulation on Various Sizes of Pipe Temperature Difference Between Steam in Pipe and Air Surrounding Pipe Pipe Size, Inches 50° 100° 150° 200° 250° 300° 350° 400° 450° 500° Per Cent Efficiencies 34 75. % 77.3% 78.9% 80.7% 82.1% 83.7% 84.8% 85.9% 87. % 88.% ^ 78.2 80. 81.6 83.2 84.4 85.7 86.7 87.7 88.5 89.3 \' 80.5 82.2 83.5 85. 86. 87.2 88.1 89. 89.7 90.4 1 Vi. 82.2 83.8 84.9 86.2 87.2 88.3 89.1 90. 90.6 91.3 83.4 84.9 86. 87.2 88.1 89.1 89.9 90.6 91.2 91.9 2 ' “ . . 85.2 86.5 87.5 88.6 89.4 90.3 91. 91.7 92.2 92.8 3 86.3 87.5 88.4 89.4 90.2 91. 91.7 92.3 92.8 93.3 87.1 88.3 89.1 90.1 90.8 91.6 92.2 92.7 93.2 93.7 3^2 87.8 88.9 89.7 90.6 91.2 92. 92.6 93.1 93.5 94. 4 88.3 89.3 90.1 90.9 91.6 92.3 92.9 93.4 93.8 94.3 4H 5 88.7 89.7 90.4 91.2 91.9 92.6 93.1 93.6 94. 94.5 89. 90. 90.7 91.5 92. 92.8 93.3 93.8 94.2 94.6 6 89.5 90.4 91.1 91.9 92. 93.1 93.6 94.1 94.5 94.8 7 89.9 90.8 91.4 92.2 92.7 93.4 93.8 94.3 94.7 95. 8 90.1 91. 91.6 92.4 92.9 93.5 94. 94.4 94.8 95.1 9 90.3 91.2 91.8 92.5 93.1 93.7 94.1 94.6 94.9 95.2 10 ... 90.5 91.4 92. 92.7 93.2 93.8 94.2 94.7 95. 95.3 Efficiencies of 3" Thick Johns-Manville Asbesto-Sponge Felted Sectional Pipe Insulation on Various Sizes of Pipe Temperature Difference Between Steam in Pipe and Air Surrounding Pipe Pipe Size, Inches 50° 100° 150° 200° 250° 300° 350° 400° 450° 500° Per Cent Efficiencies 14 76.8% 78.9% 80.6% 82.1% 83.4% 84.6% 85.8% 87. % 88.1% 89.1% ^ . 79.7 81.7 83.1 84.5 85.6 86.6 87.6 88.6 89.6 90.5 1' ‘ 81.9 83.5 84.8 86.1 87.1 88. 88.9 89.8 90.7 91.5 134 83.5 85. 86.2 87.3 88.2 89.1 89.9 90.8 91.6 92.3 ri4 84.7 86.1 87.2 88.3 89.1 89.9 90.6 91.4 92.2 92.8 2 ' 86.5 87.7 88.7 89.6 90.3 91. 91.7 92.4 93.1 93.7 234 87.5 88.7 89.6 90.5 91.1 91.7 92.4 93. 93.5 94.2 3’ 88.4 89.5 90.3 91.2 91.7 92.3 92.9 93.5 94.1 94.6 3H 89. 90. 90.8 91.6 92.1 92.7 93.3 93.8 94.4 94.8 4 89.5 90.5 91.2 92. 92.5 93. 93.6 94.1 94.6 95.1 434 89.9 90.8 91.5 92.2 92.8 93.3 93.8 94.3 94.8 95.2 5 ’ 90.2 91.1 91.8 92.5 93. 93.5 94. 94.5 95. 95.4 6 90.7 91.5 92.2 92.9 93.3 93.8 94.3 94.8 95.2 95.6 7 91.1 91.9 92.5 93.2 93.6 94.1 94.5 95. 95.4 95.8 8 91.3 92.1 92.7 93.4 93.8 94.2 94.7 95.1 95.5 95.9 9 91.5 92.3 92.9 93.5 93.9 94.4 94.8 95.2 95.6 96. 10 91.7 92.5 93. 93.6 94. 94.5 94.9 95.3 95.7 96.1 Pa^e 32 App. Ill TABLE i:0. 7, LIST PRICES OF PIPE OOVERIEG SUBJECT TO DISCOUNT Standard Thick . . Thick. . 2" Thick ♦♦Double Standard Thick . . 3" Thick Broken Joints. . INSIDE DIAMETER OF PIPE 1" iM" I'A" 2" 2H" 3" 3}^" 4" 4M" 5" 6" 7" 8" 9" 10" 12" *14" 16" 18" 20" 24" 30" $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ .22 .24 .27 .30 .33 .36 .40 .45 .50 .60 .65 .70 .80 1.00 1.10 1.20 1.30 1.85 2.10 2.35 2.60 2.85 3.30 4.00 .46 .49 .52 .56 .60 .64 .70 .76 .82 .88 .94 1.00 1.10 1.20 1.35 1.50 1.65 1.85 2.10 2.35 2.60 2.85 3.30 4.00 .75 .80 .85 .90 .95 1.00 1.05 1.15 1.25 1.35 1.45 1.55 1.70 1.85 2.00 2.20 2.40 2.70 3.00 3.30 3.60 4.00 4.50 5.50 .65 .70 .75 .80 .85 .90 1.00 1.10 1.20 1.40 1.50 1.60 1.80 2.25 2.50 2.70 2.90 4.10 4.60 5.10 5.60 6.00 7.00 8.40 1.20 1.35 1.40 1.45 1.55 1.65 1.75 1.90 2.05 2.20 2.35 2.50 2.70 2.90 3.15 3.40 3.65 4.10 4.60 5.10 5.60 6.00 7.00 8.40 3^" H" 1" IM" IH" 2" 3" 3H" 4" 5" 6" 7" 8" 9" 10" $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ Elbows 90® & 45®.. .30 .30 .30 .30 .30 .36 .42 .48 .54 .60 .72 .90 1.30 1.80 2.40 3.00 3.60 Tees .36 .36 .36 .36 .36 .42 .48 .54 .60 .75 .90 1.20 1.60 2.20 3.00 3.80 4.60 Crosses .48 .48 .48 .48 .48 .54 .60 .70 .80 .95 1.10 1.50 2.00 2.80 3.60 4.40 5.20 Globe Valves .54 .54 .54 .54 .54 .60 .78 .96 1.20 1.50 1.85 2.25 2.80 3.60 4.40 5.30 6.20 Flange Covers .50 .50 .50 .50 .50 .60 .70 .80 .90 1.00 1.30 1.60 1.90 2.20 2.50 2.90 3.30 These pipe insulations are supplied in sections three feet long, canvased and with brass lacquered bands. *85% Magnesia is made in Standard (approx. 1"). 2", Double Standard Thick and 3" (broken joint) thicknesses. For pipe sizes from and including 14" in diameter it is furnished in segmental form. Asbesto-Sponge Felted Insulation is made in thicknesses from " to 3 thicknesses 1 "and under use list prices for standard thick . Asbestocel and Air-Cell Insulations are made in M", 1", 2", and 3" thicknesses; for thicknesses 1" and under use list prices for standard thick. Zero Insulation is made in one thickness only, approximately 1 Use standard thick list prices. Prices on Zero Insulation for fittings on request. Anti-Sweat Insulation is made only in and 1" thicknesses; use standard thick list prices for all thicknesses. Fittings not made for 85% Magnesia or Wool Felt Insulations. ♦♦Applies only to 85% Magnesia. iK p^"' ■■ 4 : \ ■ '■'■lll•.‘i V'’j*s ™ BW:-1‘" 'l. :'. i mmm *'. j I' i" ^ -MW 51 M i ‘’^t‘ i^j^i T'>/iV *' '.I t . 'iv ' rT'’Ut ^w^^kSv' '...> ' r->v. .'viL-v ^ Jf'l* • ‘>v;> •’■'■■ " \T'h '^\r> ■ * ' ■'' S'f^ ■•; V^vrv , ■ ‘ . \^J|P|1K Vjk.^' : " . ,• a-..- ,™ .^h > ' - . „■ '>' ;■ ,. , - v .■ rg, :„■> ,v'5 '■‘'TV'".- ' lvV^^- .'’ 2^1 ,. ,"• ;:m ."/'i'il <: t ^ I 'ffc* .'i i . ■'.* I, :■■■'■, '’'vl^ ■ r *' sw H M ■>; ■ :•!■ v,„, ;.;gyt.ji«i- ",'fcii ../mi ' I lA’ i' •'( ’•■ ■' ^ 'r.T MW'-M:#’ — •oyyr ' * / ^ ' **' . ’*< *»' •*:? ■i Page 33 App. IV APPENDIX IV. TEE FLOW OF STEAM IE PIPES. 30 - THE BABCOCK FOHIULA. Heliable experiinental oata on the friction loss of steajE under various pressures, and particularly when superheated, are unfortunately lacking. The n;ost generally accepted forirula for steam flow is Babcock’s: P r 0,000,131 (1 + X w^ L formula (1) ^ D d5 The use of this formula may be greatly facilitated by rearrangement to the foTOiS: p r w2 L V P formula (2) or P I w^ L F formula (3) D Nomenclature: p r pressure loss, lb, per sq, in. w = steam flow, lb. per min. L r length of pipe or section, feet, D = average specific density of steam, lb, per cu. ft, V z average siiecific volume of steam, cu. ft. per lb. Note: For superheated steam use D and V for the superheated steam - not the saturated value. (See calculation, paragraph 32). d r inside diameter of pipe, inches. P a a factor vtoich is a function of the pipe diameter only, z 0.000,151 ^ (see Table No. 8). Since the value F is a function of only one variable, viz. pipe diam;eter, it may be tabulated. In Table No. 8 columns 1 and 4 indicate regularlj^ manu- factured nominal pipe sizes from l/2 inch upward. Oolumns 2 and 5 show the "actual” inside diameters corresponding to columns 1 and 4, Columns 3 and 6 indicate the values of factor ”F" to be used in formulae 2 and 3 corresponding to columns 1 and 4. 31 - STA1:DABI) and EXTHA STRONC PIPES. It should be noted particularly that column 3 applies only to standard if . ' • tjr!- <’^‘ ' ..y I I f 1 -sV-.r ». ri - 4 >i/.. $ MB , ■)' • ' '.V . '.- .■ iv , '.?' » I;' i I !? i.^ r 1 r % ■‘ V V' •<^ ; ’ >- J .■ ' 1^61 > 7 ■ ■^Ity > ♦ •> v»f< ' ff; » / > •i:i . r,:r!v«/ •■•-. ■ '< ■■'■:f,'; 'T' » ■■ . r ■' ft ■ » ffi*' • . . I f ^ : 'iw- ■! • i i y i'i ', '■^. ' . ■•’■^''T ', 'I •, ' ?i^’ 'fU-liTW I •? • , 4 .' ' V - ‘ ; , »('l ' ’ 4 ,f : ■ A . ' ' ' O Vi -', ' - •' i'lti' - , . i ' r.‘. 1 ‘ . «•-• (# 1 ®I :■ V -iv-. nbtff •r \ ‘ ^a■ lr«■^. !■ ■ r<. '.'t - Page 34 App. IV TABLE KO. 8. FAGTOH FOR THE FCLIFIED BABOOGK FORl^LA. StiiiuUircl Wcijcht PijM' F.xlra Heavy Pipe Nominal Actual J^rt ssuro Lo.ss Nominal ■ .-Vctual Prcs.sure Loss Size, Itisulo Factor, /•’ '^ize, Inskle Factor, F Inches ])iarn. Indies Diam. 1 2 3 4 5 6 i 0 022 9.5.51. X 10 ' 5 0 .540 20.51 X lO--' a. 0,824 1847. 0 . 742 340,8. 10-': 1 1 . 049 457 . 1 1 0 . 957 777.1 “ M 1 , 380 94 32 li 1 , 278 140 7 15 1.610 39.14 15 1 .500 58 . 0.5 “ 2 2 . 067 9. 519 2 1 . 939 13 . 05 25 2.409 .3510. x'lO » 25 2.323 4938. X 10-5 3 3 . 008 1017. 3 2.900 1432. 35 3 . 7)48 ■109.4 35 3 . 304 029 . 5 4 4 . 020 234.0 4 3 . 826 310.1 ■I 2 4 . oOO 120.9 15 4 . 290 105 . 8 n ,■>.017 08.54 “ 5 4.813 88 . 00 i) 6.00.) 2.5.44 0 5 .701 33 . .5 4 7 7 . 023 11.60 7 0 025 1.5.84 8 8.071 5.531. X 10 -'2 8 7 . 025 7482. X 10 s 7.981 .5870. 0 8 . 025 3890 . 9 8.941 3210. 10 9 750 2030 . 10 10 192 1012 11 10.7.50 1217. 10 10.130 1559. 12 1 1 . 7.50 704 . 1 10 10.020 1703. 13 13.000 450.5 11 1 1 . OOO 1080. 14 14.000 300 2 12 12.090 0.58.2 15 15.000 213.9 12 12.000 084.4 17 OD 10 000 153 0 13 13.2.50 407.9 18 '• 17.000 111.8 14 14.2.50 270 2 “ 20 ■■ 19.000 02 . 93 l.j 1.5,2.50 190.3 22 “ 21 ,000 37 . 57 17 OI) 16.214 M3.0 24 •• 23 . 000 23 54 18 •' 17.182 105.8 20 “ 19.182 .59.91 Pa^e 35 App. IV weight pipe, and column 6 to extra strong pipe. It might he supposed from the nearness of agreement hetv/een the actual diarrieters of standard and extra strong pipes that no distinction between the two need he made v/hen calculating pressure loss. That this supposition is erroneous may he seen hy comparing columns 3 and 6 of the table. Since the pressure loss is directly proportional to factor ”F**, the relative friction losses in the tv/o kinds of pipe for a given nominal 'size may he observed hy the ratio of the two values of factor Such a comparison reveals the fact that if column 3 he used for problems involving extra strong pipe, the error would he -10 percent for 12- inch pipe, -55 percent for 1/2- inch pipe, and the average error for all sizes from l/2-inch to 12- inch inclusive would he -28 percent. 32 - SUPERHEATED STEAl.?. Since experimiental data on the flow of superheated steam are not available, it is necessary to deduce some relation from the flov/ of saturated steam.. There are tv;o conditions which differ for wet and superheated steam, viz., surface condition and velocity. The difference in surface condition, is that in the case of superheated steam the inner pipe surface is dry, v/hereas in the case of wet steam the surface is supposedly flushed with a film^ of water. Several theories are based upon this fact. One is that the v/ater on the wetted surface fills up the irregularities in the pipe surface, resulting in a lower coefficient of friction for wet steam than for dry or superheated steam.. Another theory, exactly contradictory- to the foregoing, is that the moisture presents a more or less viscous filament v\hich imposes a drag on the flov/ing stream of vapor, and consequently the coefficient of friction should he greater for wet steam. The correctness of either of these theories has not been proved, and it is possible that both of the effects, acting in conjunction, counterbalance one another, resulting in the same coefficient of friction for superheated or dry steam as for wet steam/. The difference, in any event, is undoubtedly small, and since the effect of velocity is of considerable magnitude, the effect of surface condition may well be disregarded. The effect of the velocity of flow upon the pressure loss is not a simple one. Friction for most fluids is supposed to vary as the square of the velocity, but a studj^ of the Babcock formula shows that this relation is not universal for steam. Velocity is affected by: (1) the weight of steam flowing, (2) the cross-sectional area of the pipe, and (3) the specific volume of the steam. (1) Inspection of the Babcock formula indicates that pressure loss varies as w^ , and since the velocity is proportional to w, it follows that tlie pressure loss varies as the square of the velocity, which would be expected. (2) By plotting factor ”P* against velocity on logarithmic cross- section paper, it is found that the friction varies approximately as the 2.6 pov/er of the velocity, or som/evAiat greater than the square. The probable ex- planation is that as pipe size is aecreased, the mean hydraulic radius decreases, presenting a compairatively greater frictional surface. (3) A set of calculations v/ith saturated steam, mahing steam pressure the only variable, indicates that friction varies as the first pov/er of the 4 i i I 1 1 1 I i 1 Page 36 APP« IV velocity. The explanation of this unexpected fact probably lies in the fact that as the pressure is decreased, although the specific volume and hence velocity are greater, the density is correspondingly decreasea, and the number of molecules of steam in contact with unit surface of pipe is proportionately less. In view of the relation found in the preceding paragraph, it is the logical conclusion that, since the effect of surface condition may be disregard- ed, the friction for various amounts of superheat will vary as the first power of the velocity. The solution for pressure loss with superheated steam may be made in either of two v/ays, as will be explained. (1) Since the velocity of flow varies as the specific volume of the steam, either of the formulae, (l), (2), or (3) may be used directly by merely substituting the proper value of s]Decific density or specific volume for '*!)” or ”V" respectively from the superheated steam tables. This is the preferred method when superheated steam tables are at hand. (2) A careful examination of the properties of superheated steam indi- cates that the increase in volume at anj^ given pressure is very nearly 16 per- cent for every 100 degrees of superheat. This assumption is so nearly exact that the v/orst error due to its use is less than two percent, which is beyond criticism since there is four percent variance between the experimental co- efficients of friction as deteimiined by Babcock and Carpenter. The second method of handling superheated steam, then, is to use any reliable formula or chart designed for saturated steam, and increase the pressure loss 16 percent for every 100 degrees of superheat, 33 - EXAJlPhE OF SOLUTION BY THE FORIPLA. Data: Steam pressure - 225 lb. per sq. in, abs. Superheat - 150 deg. F. Steam Flow - 2000 lb, per min. Pipe - 12- inch extra strong. Determine: Pressure loss per 100 feet of pipe. Solution: Use formula (2) w r 2000 w^ s 4,000,000. L = 100 feet. V = 2,56 cu. ft. per lb. (from steam tables) F 2 764.1 X 10"^^ (from Table Ko. 8). p = 4,000,000 X 100 X 2.56 x 764.1 x lO'^^ _ 0,782 lb, per sq, in, 34 - ORAPHIG CHART FOR TEE BABCOCK FORJITLA. Although the solution of the miOdified formulae is quite simple v/hen Table Ko, 8 and a slide rule are available, the logarithmic chart. Fig. 6, permits a quick and easy solution of flow problemis, and it is preferred in m:Ost cases. < i I Page 38 App. IV The error involved in its use is not more than three percent if reasonable care is exercised in the solution. This form of chart was first published in 1912 by H. V. Carpenter. The original chart, hov/ever, v/as limited in its direct application to saturated steam and standard weight pipe, and the range of the quantity of flow scale was not extensive enough for many modern problems. Pig. 6 was drawn by the author to meet these criticisms and the chart as presented is practically universal in its application. 35 - EXAMPLE OF GRAPHICAL SOIUTION. The heavy dash lines on the chart indicate the solution of the same problem as solved under "Examiple of Solution by the Formula". The solution is self-explanatory and needs no further comirient. T >*