Document KJNb8Z7nE9rJkm6wo559ojxO6

FILE NAME: Power Generation (POW) DATE: 1951 Jan DOC#: POW015 DOCUMENT DESCRIPTION: Published Article from Trade Journal JANUARY M 1951 * m? V O L U M E 95 NUMBER 1 FEATURE ARTICLES Oil from shale--is it coming soon? Ten easy steps for selecting pipe hangers S p read er stokers pass rigid load tests with flying colors How to size up the atom bom b--pcfltf three Acid cleaning: pow er-plant maintenance tool Three refrigerating plants serve cooling and freezing loads Take the mess out of oil-tank gaging G uide for over-potential test on units in service How to choose your diesel cooling system I Rotor repair a tjsla n t saves time and expense of shipping Skid-based diesel central stations in Mexico Air m apping of coal piles saves cash How plant lubrication pays off Forty years' experience a t Kilbourn Hydro Plant How your steam turbine is insulated Tenth annual convention of Institute of Power Engineers Which h ap p e n ed first: low w ater or ruptured tube? O cean is put into another 'test tube' 71 75 78 82 89 92 95 9 98 102 103 107 108 112 116 118 119 140 DEPARTMENTS Electronics: m otor an d g en erato r exciters--No. 33 in a series Power engineers' notebook 126 Data sheet Problems from the plant 130 Plant equipment news Technical briefs 134 George Edwards News of the pow er field 138 Readers' service page 122 142 144 154 192a January 1951 POWER (M em ber ABC and ABP) Voi 95--No. I Power (w ith which are consolidated Science and Industry, The Engineer Review, The Engineer and The Stationary E n g in ee r), is published monthly with an additional directory num ber in June, by McG-aw-HiII P ublishing Com pany. Inc, Jam es H M cilraw (1860-1948), Founder. PU B LICA TIO N O F F IC E : M cC R A W -H ILL B U ILD IN G , 330 W 42ND ST, N EW YORK IS, N . Y. E X E C U T IV E , E D IT O R IA L and A D V ER TISIN G O FFIC E S: 330 W 42nd S t. N ew Y ork IS, N. Y. C urtis W M cGraw, President; W illard Chevalier, Executive V ice-President; Joseph A G erardi, V ice-President and T reasurer; John J Cooke, Secretary; P aul M ontgomery, Senior VicePresident, Publications Division; R alph B Sm ith, Editorial Director: Nelson Bond, V ice-President and Director of A dvertising; J E Blackburn, Vice-President and D irector of Circulation. S U B S C R IP T IO N S : A ddress correspondence to P ower, S ubscription Service, 330 W 42nd St, N ew Y ork 18, N . Y . Allow te n days f o r change o f address. Please in d ic a te p o sition a n d com pany connection on orders. Single copies 65c. Subscription ra te s --U . S. and U. S. possessions: $5.00 fo r one year. $7.00 fo r tw o y e ars. C a n a d a : $7.00 fo r one y e a r, $11.00 fo r tw o years. P a n -A m e ric a n c o u n trie s : $10.00 for one year. $16.00 fo r tw o years. All o th er countries: $15.00 fo r one year, $25.00 fo r tw o years. E n te re d a s second-class m a tte r J a n u a r y 26, 1949 a t the p o st office a t N ew Y ork, N . Y . u n d e r A ct o f M arch 3, 1879. P r in te d in U . S . A . C o p y rig h t 1950 by M cG raw -H ill P u b lish in g Com pany, Inc. All rig h ts reserved. P ower articles a re indexed in both th e Industrial A rts Index and the E ngineering Index. P ower publishes its ow n in d ex a n n u ally , copies o f w hich a re available on re q u e st to th e e d ito ria l offices. ALUMINUM, and its power supply, holds center of stage as mobilization hits high gear. Leading producers have been asked to plan for a 2-billion-lb-pcr-yr expansion --that means more than 2 million kw. Preliminary indications are that some new capacity will be gas-engine power (like Alma's Point Comfort works) while some will be steam plants burning gas or, possibly, coal at the mine mouth. Whatever form new aluminum capacity takes, we'll probably see scenes like our cover repeated. In that photo, a worker at the Westinghouse East Pittsburgh works solders armature connections on a synchro nous-converter collector. Next month . . . Another installment of Phil Swain's popular insulation handbook-- practical dope on asbestos, insulating concrete, aluminum foil and other modern mate rials for cutting heat loss. * All eyes still focus on America's first commercial power-producing gas tur bine-- the unit at what used to be called Huey Station (now Belle Isle). Last February we brought you Oklahoma Gas and Electric Co's first operating report on this installation. Next month w ell auu another year to the record. Performance still looks good! For years, paper-industry engineers have wrestled with the problem of dis posing of sulfite liquor. Back in Janu ary 1949, we told of a new magnesiumbase process that forms one solution. Now experiments show calcium-base sulfite liquor-- the common garden vari ety-- can be burned successfully without auxiliary fuel. February article reveals how it's done, possible applications. Free-piston Compressors have been interesting American engineers because they look good for gas-turbine plants. They also do a job as self-powered air compressors-- witness our February re port on developments in France. . . . and future months Watch for the new, revised edition of the Power Handbook-- bigger and bet ter than ever! First part now scheduled for March, second part for June. SHEET-METAL JACKETING gives compact finished appearance sulation just as earlier lagging did. It also provides i to unit besides performing practical function to protecting in- air-insulated space for all piping and auxiliary equipm * { How Your Steam Turbine Is Insulated By C H TeBRAKE, Steam-Turbine Dept, Allis-Chalmers Mfg Co I n t h e e a r l y d a y s , little thought was given to heat loss from piping and engine parts. Steam pressures and temperatures were low, and fuel cost was reasonable. Some lagging was used, but primarily to protect operating per sonnel from burns. It also hf.'ped to reduce boiler and turbine-room temper atures. Early forms of lagging included wood, rags, gypsum plaster, and some types of clay used with mixtures of rope fiber, straw and hair as binding material. During the early 1880's carbonate of magnesia began to be applied as in sulating material to water and other fluid vessels. We have no data on the type of insulation used on the first turbine built (in 1905) by our com pany. Probably it was magnesia, ap plied as plastic material in layers of about 1% in. at areas of highest temperatures. Heat Conservation. Operating tem peratures have steadily risen, paced by increasing fuel costs. Adequate in sulation on steam turbines became an important consideration. Heat radiated to surrounding air reduces efficiency of the entire plant cycle. X _ 16 Possible distortion of the turbine cylinder by subjecting one side to cold drafts creates an operating hazard. Under severe conditions this causes misalignment ar\d damage to moving parts. \ These conditions of .ass and hazard can be controlled with various forms and combinations of magnesia and as bestos insulating materials. Insulation. For surfaces with tem peratures at and below 500 F, 85% magnesia has proved most economical. This material contains hydrated basic carbonate of magnesium, bonded with about 15% of asbestos fiber. The mag nesia is the chief insulating component in this mixture because of its high percentage of minute dead air spaces that it contains. Ttfe asbestos fibers act as a heat-resisting reinforcement to add structural strength and long life. This material handles easily. It is clean, light and inorganic in nature. It does not char, burn, shrink or loosen in service. It has no corrosive action on the metal it touches. When temperatures do not exceed 500 F, insulation of pipes and surfaces utilizes 85% magnesia in block or sec tional form, applied in one or `tl layers to the total thickness need for the temperature. An exception; . made for pipelines, 2 in. and smalli These are insulated to a maximum thic ness of 2 in. In applying block insulation, i joints and crevices are filled with pli tic cement of like material. Where tj layers are needed the joints are brok or staggered. After fastening the s< , mental insulation in place with n{ 1 corrosive wire, the entire outer surfa is coated with %-in. thickness of j bestos cement in two layers. Gab nized wire mesh reinforces the ceme: which is troweled to a smooth, ha finish. Instead of a metal-jacket Ii ging, the exposed surface may be c< ered with a canvas jacket wrung 4 in cold-water paste, then pasted a stapled in place. Subjecting 85% magnesia to te peratures above 500 F tends to calci it on the hot surface. This produce^ thick film of magnesium oxide, whj possesses high insulating qualities I lacks structural strength. For this rj son, a combination of insulation blotj' is provided, which has an inner laj ) P O W E R January H BLOCK AND PLASTIC insulation cover turbine hydraulic throttle valve, strainer INSULATING BLANKETS over the flange joints are easy to remove for repairs i i iNSULATION FORMS INTERMEDIATE SURFACE between turbine-casing surface and vhect-metal jacketing'. Casing doors open to give access to piping and auxiliaries Function of steam-turbine insulation has changed over the years. Here's an authoritative description of the need for insulation and how it is applied to the units LUGS IN PLASTIC insulation make an chor points for blankets covering joint withstand the higher temperatures i ad preserve all the inherent qualities of the 85% magnesia. Specially se lected precalcined diatomaceous silica, fclendciFand bonded with asbestos fiber, composes the inner layer. Such ma id ial, though high in refractory value, is usually lower in insulating value and higher in cost than 85% magnesia. Thickness of the high refractory layer i* kept to the minimum needed to asure an interface temperature of not over 500 F. Insulating Blankets. Because oper ating conditions involve temperatures ailing for insulation thickness up to 1 in. or more, removal of insulation for turbine inspection and repair is usually difficult, destructive and costly. To avoid the necessity of breaking the insulation on flanges and covers that mun be dismantled occasionally, a blanket type of material is made. These blankets consist of asbestos cloth in mattress form. Three types of asbestos are commonly lt=ed in the insulation field. They all belong to the fibrous variety of horn blende, one of the amphibole minerals composed mainly of silica, magnesium and calcium. They often contain alumi num and iron. Chrysotile, or white as bestos, has extremely fine, strong and elastic fibers, can be spun and woven, ideal for cord and cloth materials. Crocidolite, usually called blue as bestos because of the dull lavender color given by its iron content, com pares with white asbestos in its physi cal and insulating qualities. Amosite, or brown asbestos, is comparable to white and blue asbestos in many ways, but has somewhat shorter fibers. Be cause of its lower cost, this material is used extensively for reinforcement of the magnesia blocks and for filling in the mattress type of covering. Blanket cloth is usually woven of white asbestos. For high temperatures the cloth is woven of monel-wire-insert ed yarn and sewed with yarn of the same material. The stuffing is usually brown asbestos, made with a uniform thickness and density of not less than 12 lb per cu ft. All blankets are closely tufted to prevent sagging. They are fitted with hooks or rings for attaching to sur faces to be insulated. Blankets are usually applied to horizontal flanges of the cylinder casing, throttle valve cover and connecting flanges, steam strainer cover, and such other surfaces as will require dismantling. The blanket is applied in one or two layers to the total thickness needed for the temperature, in general, blankets are arranged in two layers with joints staggered, ex cept where cap or muff types lend themselves more readily as on pipe flanges or vessel covers. For the latter, single layers are made up as needed. A noncorrosive wire, such as monel, is used to lace the blankets together and to the lugs, which are screwed or welded to the surfaces to be covered. Insulation methods we have talked about have been used for many years, though we have always been alert for improved and more economical methods. There are, of course, many other types of insulating materials, such as rock wool, spun glass, aluminum foil, etc. Moreover, the industry is al ways developing new materials and methods for reducing heat losses. Each material possesses qualities that make them most suitable for certain specific applications and should be used where experience has proved them best. P O WE R January 1951 117 We have been asked: i Can insulation save my buying a new feed water heater? Here's what a manufacturer wrote us recently: "Our factory uses steam for processing. Con densate return lines, which are now uninsulated, total 2106 feet in length. Our peak loads average 3 hours daily, and the feed water heater can furnish only 80% of recently increased load. Of course, this makes steam costly and inadequate for full production. Will it be necessary to buy a new feed water heater to increase the efficiency of our boiler, or can the application pf insula tion to the condensate lines do the job?" Here's what we advised: While an additional feed water heater might solve your problem, it isn't necessary. Insulating your condensate lines will prevent loss of heat on the way back to the boiler and consequently will increase I filer efficiency. Too, insulating the lines will cr A far less than installing a new feed water heater. The question then is--which kind of insulation will Armstrong engineers run across questions like this every day. Helping to solve these problems do the best job? Air-cell pipe covering would has given them valuable knowledge that could 1- i be adequate if peak loads were brief and oc be put to work on your next insulation problem. casional and return lines were short. However, You:ll find these trained engineers in the loads here are too heavy and the lines too your near-by Armstrong office, and long to make air-cell desirable. they will be glad to help you. Insulation of the return line with 85% Mag nesia pipe covering is the best way to attain economical operation. The extra^cost of this type of insulation will be repaid, under present con ditions, within just a few months. IF YOU HAVE ANY QUESTIONS involving industrial in sulations for low- or high-temperature applications, we'll do our best to help you solve them. Ju st address a letter or post card to Armstrong Cork Company, 7001 Maple Avenue, Lancaster, Pennsylvania. r i T 7 T T'TT'TTT"