Document k6pgeDZv21nJGR7nr52L1GNNV

FILE NAME: Power Generation (POW) DATE: 1950 May DOC#: POW012 DOCUMENT DESCRIPTION: Published Article from Trade Journal f F p r V t h P W SWAIN Editor L N ROWLEY Executive Editor J F A-vANNETT Associate Editor " j C McCABE B G A SKROTZKI Associate Editor Associate Editor J J O'CONNOR C F SANDERS C F MARSCHALEK Assistant Editor Assistant Editor Art Editor SHELTON FISHER Publisher W J HARING Sales Manager W a sh in g to n : GEORGE B BRYANT JR A tla n ta : EARLE MAULDIN WORLD NEWS OFFICES! L o n d o n , P a ris , F ra n k fu r t, T o k y o , M e lb o u rn e , R io d e J a n e ir o , Mexico C ity .ky^riKut U* bUBJb^ KIH IHt i MAY 1950 VOL 94 NO. 5 PLANT OPERATING METHODS, MAINTENANCE AND SAFETY < v. "-CiS v. vi n i M a ' r. ~ STEAM GENERATION, FUELS, FIRING AND COMBUSTION TURBINES, ENGINES, AUXILIARIES; HYDRO POWER DIESELS, GAS ENGINES AND ACCESSORIES I.?TM:0; AIR - $$X'<$'v CONDITIONING AND \ r " " v. REFRIGERATION v' ; ' -v, ' , | ELECTRICAL EQUIPMENT, ELEVATORS PIPING, VALVES AND SPECIALTIES -r \ -- ' ---- --- - i.- .. ...V , , - w-,v. TRANSM ISSION, LUBRICATION !';r STEAM SER V IC ES, HEATING a- - - ......... .. v INSTRUMENTS, CONTROLS PUMPS, COMPRESSORS M acy's installs 5 0 0 0 kilowatts o mercury-arc ignitrn rectifiers................... 76 First coal-burning gas turbine piles up hours........................................................ 80 Answers to your questions on hydraulic ash handling..................................... 83 A re your motors overheating?..................................... ....................................... 87 Putting water hammer under co ntro l........................................................................ 9 0 M echanic^ vibrations: Cause and control -- 1 ................................................... 92 Split air-conditioning system raises textile plant's profits 94 Insulation handbook: 3 -- W hich thickness pays best? ......................... 98 New diesel delivers more power in same sp a c e ................................................. 100 Tools for saving cooling water -- tower types and uses.....................................102 What about the hydrogen b o m b ? ........................................................................... 107 . -betters from a turbine specialist -- 7 ...................................................................... 111 Early planning provides water for boiler washing, startup.............................. 2 Making lubrication hazard-free................................................................................. 116 How power services work for auto maker..............................................................117 Power rake cleans pump's trash racks...................................................................... 121 4 j ! "I ?14. i* ? ' 4 4 . -i 4 Electronics: 25 -- Smoke-density indicators: Part I Power engineer's notebook of plant-tested ideas Problems fresh from the plant................................. Technical briefs for busy power m en.................... News of the power field. . . . 138 Engineer's bookshelf Data sheet.............................. . . 142 George Edwards. Plant-equipment news......... . . .1 4 4 Readers' service page Cover photo taken in feed-pump area of recently expanded boiler house at Cities Service Co's E ast Chicago refinery. Courtesy of M W Kellogg Co, who handled the refinery modernization, including new boiler and renovation of feedwater system .122 126 .1 3 0 .134 .154 .1 5 6 192a VOLUME 94, NUMBER S A B C ABP C O P Y R IG H T 1950 by M cG R A W -H IU P U B LISH IN G C O ., IN C . ALL RIG H TS RESERVED Jomes H McGraw (1860-1948), Founder; Curtis W. McGraw, President; Willard Chevalier, Executive Vice-President; Joseph A Gerardi, Secretary and Treas urer; Paul Montgomery, Senior Vice-President, Publications Division; Nelson Bond, Vice-President and Director of Advertising; J E Blackburn Jr, Vice-President ond Director of Circulation DISTRICT MANAGERS'; New York, W W Quarles; Philadelphia, C R Long; Cleveland, N O Wynkoop Jr; Chicago C Bouahton : , L K,n9; Boston, J E Slater; St. Louis, C Boughton PUBLICATION OFFICE; 418 West 25th St, New York 1, N. Y. EDITORIAL AND EXECUTIVE OFFICE p 0 W 42nd St, New York 18 N Y Cable Address; "McGraw-Hill New York DISTRICT OFFICES; 520 N. Michigan Ave., CHICAGO 11; 8 Post St San "nasco; National Press Bldg, Washington 4; Architects Bldg, Philadelphia 3; 738-9 Oliver Bldg, Pittsburgh 22; 1510 Hanna Bldg, Cleveland 15; 2980 Penob scot Bldg, Detroit 26; Continental Bldg, St. Louis 8; 1427 Statler Bldg, Boston 16'; 1011 Rhodes-Haverty Bldg, Atlanta 3 ; Pacific Finance Bldg", Los Angeles >4; Aldwych House, Aldwych London WC2 POWER articles are indexed in bsth the Industrial Arts and the Engineering Index POWER issues its own ndex annually; copies are available on request to the editorial offices, 330 W 42nd St, New York 18. P O W E R May 1950 71 IF YOU COULD BUY ONE OR M ORE OF THESE BONDS, WHICH WOULD Insulation Handbook: Part 3 Which Thickness Pays Best? How l hick, should heat insulation be? The thicker the insulation, the more heat saved. But how do you figure how much is enough? It's important to think straight on this matter before plunging into a lot of practical details, so this brief article will concentrate on the reasoning. After the logic is clear, the practical applica tion will be easy. As an investment, heat insulation differs from security investment in sev eral respects. First, when you apply a reasonable thickness of insulation to a heated surface you often get a yearly return of more than 100% on your money--and with all the safety of Government bonds. Yet few of us will become millionaires by this kind of investment because the amount we can invest is always limited by the area of the existing bare heated surfaces in our plants. Nor can we get rich by building up the insulation thickness indefinitely. Heat and dollar loss from the bare surface puts an absolute ceiling on the possible savings by any conceivable thickness of insulation. The first inch or two plugs most of this hare-surface loss. All subsequent inches can do is to save part of what would escape from the tinder layers alone. This line of thought leads directly to the standard method of finding the so-called "economic thickness" -- the thickness that is the wisest investment. Strange to say, this is not the same as the thickness that yields the highest percentage return on the total dollars invested. In fact the thinnest available commercial thickness generally yields Editor Phil S w a in te lls w h y the thinnest insulation generally p a y s out the fastest, y e t is ra re ly th e best in vestm en t. Future chapters w ill tell m ore about heat and d o llar savings-- also , h o w to select an d a p p ly the v a rio u s in su latin g m aterials iht- highest percentage return, yet is rarely the best investment. Like Buying Bonds. To clear up this puzzle let's think through a parallel case in an imaginary investment market. Suppose some very good friend should olfer to sell you the unusual bonds pic tured at the top of this page. He will let you buy any you wish for $100 each, but only one of each. Let's assume, in this imaginary case, that the safety of both interest and principal is beyond question. Naturally you reach first for bond A. In this deal you make no mistake. You will get $24 per year for your $Mf), and that's 24%. Nor do you hesitate about buying bond B, which is good for 12% per year, on your second $100. Unless you are hard pressed for cash, you will probably find bond C, paying 6%, also worth while. We shall assume that you are not interested in getting 3% on bond D. So, for $300 you buy a of 24 -j- 12 -f- 6 = $42 Now certainly every move you have made lias shown, sound business judg ment. Yet when you added bond B to bond A you cut your percentage return on your total investment from 24% to 18%. Adding C reduced it to 14%. Highest Return, Wisest Buy. So here you have a strange situation where an 18% return is more "profitable" than a 24% return, and a 14% return more profitable than an 18% return. What you have done is to assume a series of small limited investments ar ranged in decreasing order of attractive ness. You start at the head of the list and work down, taking each in turn until you reach one that ceases to at tract. Then you stop. You have made the wisest total use of your money, yet you are surely getting a smaller per centage return on your investment than if you had stopped.with the most favor able investment item offered. Figuring Economic Thickness. Now', this imaginary bond-buying setup ex actly parallels what an.engineer, skilled in heat-insulation economics, does when he selects the "economic thickness" of insulation for a given set of conditions. He considers the various thicknesses commercially available and figijtjgs ^,r each the total yearly heat loss in dollar*11is first (and best I investment is 1"' first thin layer applied to the bare sur face. Next he figures how much more 98 P O W E R May I95(P SELECT? THAT' S HOW YOU DECIDE TH E THIC KNESS OF HEAT INSULATION A .Yields 24% A This is good. A r B.................................... Yields 18% This is better. A+ B i C Yields 14 ^ This is still better. A+ B +C+ D Yields 11 % Not so good. next thickness costs and how much it will save. If this additional is an adequate return on the investment, lie decides to go far. he treats the next possible step same way--and so on until he the point where the game is no worth the candle, the point any further increase in thickness yield a reasonable return. That proper stopping point, tin* ecothickness. Up Sheets. Now let's work out for an idealized ease where the is available in flat sheets 1 in. and costing $1.00 each. Assume these can be stacked up on a level surface without any installation also, that heat losses (in are as indicated in Table I for area covered by the sheets. the first layer is truly a wonderinvestment, paying 150% yearly, the first layer on. however, there no further opportunity for such a killing, but the 22% return on a second layer is still attractive. Usually the own er will also be interested in the 9% re turn on the third layer, but probably not in the 5% on the fourth. Here, then, the economic thickness (the best all-around investment) is the .'5-in. Yet, as shown in column 5 of Table T. the percent return on th e total invest ment is 150% for 1-in., 86% for 2-in. and 60% for 3-in. Here, as with the bonds, the minimum investment is not the best investment, although it yields the highest percentage return. Practical Example. Turning from this simplified case to an actual situation, we note several differences. First, the greater thickness considered may not be obtained by adding layers, but by substituting thicker layers. Yet the same logic holds here. We merely con sider the difference in cost and the difference in yearly saving for each step in thickness. Again, in our simple illustration, we neglected the cost of application. We also assumed that each layer cost the same as every other. Obviously the applied cost of 2-in.-thick insulation will be less than double that for 1-dn. Table II gets down to a practical case. Columns 2 and 3 show, respectively, actual contract prices for a complete job (insulation of a heater) and actual yearly heat losses in dollars. Note that the half-inch increment from 2% in', to 3 in. pays 13% while that front 3 to 3Y> pays 9%, indicating that either 3-in. or 3%-in. total thickness would he reason able. Most plants would not consider the 5% return for the next increment worth while, so would stop with 31-in. thick ness. In any given case the choice will depend on the ease of getting invest ment money, other possible uses for the available cash, the stability of the busi ness, and other local factors. Later chapters of this handbook will show how to figure losses for various thicknesses and how to determine the economic thickness of heat insulation for specific conditions. - - EFFECT OF STACKING UP LAYERS 1 INCH THICK Wo. of * y o rs 0 fi ; 4 T o ta l in vest m ent, $ 0 1.00 2.00 T o ta l yea rly loss, $ 2.00 0.50 0.28 T o ta l yea rly saving, $ _ 1.50 1.72 % retu rn on total in vest m ent _ 150 86 In ve st m e n t in last la y er, $ __ 1.00 1.00 Y e a rly sa v in g s. la st layer, $ _ ....... % re tu rn , la st la y e r _ 1.50 150 0.22 22 3 3.00 0.19 1.81 4 4.00 0.14 1.86 60 1.00 0.09 9 46 1.00 0.05 5 II: BID ANALYSIS FOR INSULATING HEATER T h i c k - __ ness. in . T o ta l cost in sta lle d , $ 6 0 l 200 1V i 260 2 318 2V i 374 _3l 429 3 1i 484 4 539 T o ta l yea rly heat loss, S 360 90 63 48 38 31 26 23 Cost of in crem en t of th ick ness, $ _ 200 60 58 56 55 55 55 Yearly sap- in g from in crem en t S ` r __ 270 135 27 45 15 26 10 18 7 13 5 9 3 5 Bo v v e r May .1950 99 SELECT? THAT' S HOW YOU D ECID E T H E THICKNESS OF HEAT INSULATION A Yields24 % `'This is good. A+ B .................................... Yields 18 ^ This is better. A+ B+ C Yields 1 4 % < This is still better. A+ B+C+ D Yields 1 1 % Not so good. the next thickness costs and how much killing, but the 22% return on a seco^tk also assumed that each layer cost the it will save. If this additional layer is still attractive. Usually the <vri?; (Bgjne as every other. Obviously the saving is an adequate return on the er will also be interested in the 9%We- applied cost of 2-in.-thick insulation f- additional investment, he decides to go that far. Then he treats the next possible step lurn on the third layer, but probably not in the 5% on the fourth. Here, then, the economic thickness will be less than double that for 1-dn. Table II gets down to a practical case. Columns 2 and 3 show, respectively, in the same way--and so on until he (the best all-around investment) is the actual contract prices for a complete reaches the point where the game is no .'5-in. job (insulation of a heater) and actual longer worth the candle, the point Yet. as shown in column 5 of Table yearly heat losses in dollars. Note that where any further increase in thickness I. the percent return on the total invest the half-inch increment from 2% in', to doesn't yield a reasonable return. That ment is 130% for 1-in., 86% for 2-in. 3 in. pays 13% while that from 3 to 3% : is the proper slopping point, the eco and 60' r for 3-in. Here, as with the pays 9%, indicating that either 3-in. or i nomic thickness. bonds, the minimum investment is not 3%-in. total thickness would be reason Stacking Up Sheets. Now let's work llie bc-t investment, although it yields able. this out for an idealized ea.-e where the the highe-t percentage return. Most plants would not consider the insulation is available in flat sheets 1 in. Practical Example. Turning from this 3% return for the next increment worth thick and costing 81.00 each. Assume simplified ease to an actual situation, while, so would stop with S^-j-in. thick that these can be stacked iqi on a level we note several differences. First, the ness. In any given case the choice will heated surface without any installation greater thickness considered may not depend on the ease of getting invest cost. be obtained by adding layers, but by ment money, other possible uses for the Assume, also, that beat losses (in substituting thicker layers. Yet the available cash, the stability of the busi dollars) are as indicated in Table 1 for same logic holds here. We merely con ness, and other local factors. the area covered by the sheets. sider the difference in cost and the Later chapters of this handbook will Here the first layer is truly a wonder difference in yearly saving for each step show bow- to figure losses for various ful investment, paying 130% yearly. in thickness. thicknesses and bow to determine the With the first layer on. however, there Vgain. in our simple illustration, we economic thickness of heat insulation is no further opportunity for such a neglected the cost of application. We for specific conditions. EFFECT OF STACKING UP LAYERS 1 INCH THICK T o ta l in y e st*rnen t, $ 0 1.00 2.00 3.00 4.00 T o ta l yea rly loss, $ 2.00 0.50 0.28 T o ta l yea rly saving. 5 ___ 1.50 1.72 c/c r e t u r n on total in vest m ent ___ 150 86 0.19 1 81 60 0.14 1.80 46 In vest m en t in last la y er.' S ___ Y e a rly sa v in g s, la st layer, $ ___ 1.00 1.50 1.00 0.22 w. 1.00 1.00 0.09 0.05 % retu rn , la st la y e r ____ 150 22 9 5 II: BID ANALYSIS FOR INSULATING HEATER T h ick ness, in . 0 1 1 Vi 2 2 3 3 l < 4 T o ta l cost in sta lle d , 5 0 200 260 318 374 429 484 539 T o ta l yea rly heat loss, $ 360 90 63 48 38 31 26 23 Cost of in crem en t of th ick ness, $ -- 200 60 58 56 55 55 55 Yearly sav- in g fro m in crem ent $ % -- -- 270 135 27 45 15 26 10 18 7 13 5 9 3 5 i 0 W E R . May 1950 99 II 1 li 1 W h a t 's w ro n g with this p ictu re ? This m an is insulating these exposed w ater tubes the h a rd w ay. H e 's covering each tu b e sep arately , instead of insulating the group as a single unit. W hen boiler tubes, or any other group of hot lines, operate at the same tem peratures and are as close together as these, it takes less tim e and less m aterial to insu late them as one unit. T his m ethod is shown in the small illustration below. It also cuts dow n the area of exposed insulation surface, thus reducing the am ount of heat lost by radiation. H alf sections of pipe covering are used on the outside lines, then all lines are boxed in together w ith insulating block. O f course, if th e lines are spaced too far apart, or if they m ust be read ily, accessible for m ain ten an ce, each line should be insulated separately. Sometimes whether to insulate pip ing singly or as a unit m ay be a pretty close decision. At other tim es, the answ er m ay be obvious. B u t there is alw ays one best w ay of doing this job, ju st as there is for every other phase of heat insulation work. In cases like this, A rm strong engineers are trained to recom m end the least expensive and m ost efficient m ethods. The com plete contracting service they represent also supplies you w ith top-quality insulation m aterials and sundries, applied by skilled A rm strong installation crews. If you consult an Arm strong en gineer the next tim e you plan a heat insulation job, his advice m ay save you tim e and money. His serv ices are alw ays available w ithout ob ligation. C all the A rm strong office nearest you or write to A rm strong C ork C om pany, 7005 M aple Ave., L ancaster, Pa. f. 4 - . , \ Y VI > [ , i p r H : 1 t > 't.* U%.TC - / I lJ L I t i t 'O l N V jr O JLi \ jO' t J L > M Ja.W/JLx-'Vin.^ JLi \ k ) jL L i . O I ; I - l MATERIALS - INSTALLATION : i FOR ALL TEMPERATURES FROM 300F. BELOW ZERO TO 2800F. %) P O W E R . May 1950 181 :.i- i In most businesses, operating costs are still on the rise. But there's one man who can do something about it--he's the man whose job is to get maximum heat and power from fuel dollars. He knows you get maximum efficiency from Eagle-Picher Industrial Insulations because they're made of durable, chemically and physically stable mineral wool, noted for its low conductivity. They give long years of service and are easy to maintain and replace. There's an Eagle-Picher insulation that can help re duce your operating expenses! Let these Eagle-Picher products also saveyou m oney. . . pow er. . . time Insulating Felts Supertem p Block Blankets Loose W ool Pipe Covering Stalastic Insulseal Insulstic Sw etchek Finishing Cem ents Insulating Cem ents TFT f/ ei i e- p e c:r-r r r r & General Offices: Cincinnati (1), Ohio Since 1843 :f i Insulation products of efficient mineral wool--for a full range of high and low temperatures. Technical data on request. p tm m 185