Document 7MkkVaGjvYay8a332yZZNabzg

TABLE I--PHTSICAl CHARACTERISTICS OF TYPICAL 1500-KW STEEL-HILL 6AS ENGINE INGINt (NO Ploor.spaee occupied by one unit Height above Aoor (over flywheel) Nutnbet of cylinder* Cylinder size Cronkpin 2400 sq ft 18 ft, 4( in. 4 47-in. din x 60 In. 32-in. din i 16 in. Crocshead pine Main bearing* Shaft din at center Flywheel din Cooling water 15-in. din z 17 la. 50-in. din x 54 in. 56 in. 28 ft 16,500 gph Oa* consumption (normal load) Thermal efficiency (lees wo*te-he*t boiler) Complete engine, wt (including flywheel) Frame, wt Cylinder, wt (without valve* or gear*) 455,000 cfh ' 26.0% 1,500.000 lb 167,0001b 5S.000 lb Connecting rod, wt Bhaft, wt 8haft, wt (with crank* and wheel hub) Main crosshead, wt Pifton, art 14,000 lb 72,000tb 196,000tb 11.000 lb 5600lb Piston rod, wt Flywheel, wt 7400\b 260.0001b GINIRATOR (NO Field pole*, number Rating at 0.B pf, continuous Current 54 2500 kw 25 cycles, 3 phase, 6600 v Efficiency (full load) Rotor, wt Complete generator, wt 91% . 65.000 1b 134.0001b ard procedure. Time required to bring an engine up to load hinges on the length of time it has been oQ the line as welt as number and type of repair* made while it was out of service. As an example, some repairs require "run* ning-in" time and an engine may be run for as much as 20 to 50 min for this operation before having any load put on it. Again, If an engine bas been down some lime and all parts are cold, allowance must be made for heating It up to difficulties from uneven expansion ean be avoided. Cast-iron liners cov ered with a layer of insulation and housed In steel shells act as the exit channel (or exhaust gas from the en gines. They undergo considerable ex pansion and growth in starting up so allowance must be made for this action. Normally, starting up with a warm engine takes less than 5 min. Com' pressed air at 250 psi admitted through cam-operated air-starter valves turns the engine over. During this turning-over period gas is gradually introduced until a combustible mixture Is available. Al ter it Is in the cylinders, the com pressed-air supply goes off and engioe is brought up to speed under manual control with visual guidance from a synchroscope. Once it indicstes the en gine is up to exact speed the generator is put on tho line. Load scheduling lor these engines Is made oh their duly as base-load units. They can carry reduced loads but within definite limits. With steam turbines also delivering energy the usual practice is to take advantage of the tur bine's batter ability to follow any load . variation. . Engine exhaust passes through east- TABLE II--HEAT BALANCE Typical Gas Engine end Boiler Net power generation Steam generation Lots to cooling water Lots to boiler blowdown Loss to sensible heat In stack gas Lon to CO In stack gas Radiation and unaccounted for . M Btu 12,683 13,965 12,040 913 4,691 2.396 Percent 27.16 29.94 25.78 1.95 10.04 0.00 5.13 Boiler But Balance Steam generation Loss to blowdown Loss to sensible heat in stack gas Radiation and unaccounted for 46,708 100.00 13.983 913 4,691 243 70.51 4.60 23.66 1.23 Engine Neat Balance Net power generation Loss to cooling water Radiation, mechanical and electrical losses 19,850 100.00 12.663 12.040 3,155 47.18 44.60 8.02 26.678 100.00 iron liners, and enters waste-heat boil ers. Exhaust-gas temperature entering the boilers runs about 1200 F. These are vertical watertube units equipped with economixers and superheaters, cap able of reducing engine exhaust from 1200 to 3S0 F. Some deliver steam at 165 psi, others at 275 psi, with capaci ties from 2 to 4 lb per kwhr. Feedwater for the boilers acts first as a cooling agent for pistons, cylinder jackets, cylinder heads and exhaust valves. About 18,500 gal per hr pass through the engine to experience a .temperature rise of about 60. F. . This heat pickup is credited to the engia* In computing its thermal efficiencyTable II gives a typical heat balance from a paper by T A Lewis, superin tendent, service div, Bethlehem plant. ' Bethlehem Steel, presented before the' Association of Iron and Steel en gineers. A definitely scheduled maintenance program is carried out for all gaselectric engine*. It consists of a shut down about every 600 hr to check bear ings, piston-rod alignment,, cylinder lu brication, generator clearance, etc, nod to flash cooling-water jackets., . .404 (0| 7,0 J#ayv. d,941 v M i'&i'dV WJ-yS* -Sv -V * f \rV\ i;, *o:v5(V>'C*{W);'usrhlVfdriftl'rf;pptpl`-l<HQH*p*ii*nglneer, '*$ '* ^vertiralMurblns-pjjmp j.dtvhlon, V Kvr-'-JV1'! Worthington,vglvesy .A i I - trouble!; remedlei K yv k. -.w.-iV-.'C:-i.-`t !. > =3573 1--Service, Drives, Construction q j. .yfrfft l a nertleol-turOln* ten- irf/ofol pump? A^It is .a vertical-shaft, diffuser, single- or multi-stage centrifugal pump with the pumping element suspended from the discharge piping, fig- 2 and 2. Needs of a given installation deter mine leogih of discharge piping. Pump ing bowl, B, may connect directly to the discharge head, as In close-coupled pumps for shallow pits or sump serv ice. Under such conditions there may be no discharge piping. These pumps, originally designed for raising water from wells, hove been variously knows as dcepwell, turbinewell or borehole pumps. Vertical-tur bine pump U now the accepted term. Q 2*--(Thai Is the difference between e vtrtleoUarbine pump and vertical wst-pll propeller pompf A--The basic difference between these units is specific epced. Although there are generally no limitations, ver tical-turbine pumps are ol medium specific speed and wet-pit propeller pumps ol high specific-speed design. Vertical-turbine pumps ore suitable far installation In cased wells; by amlti-steging, heads as high as 1000' ft can be obtained. Vertical wet-pit propeller pumps are "ad for open-pit or sump service. For th stme capacity and operating speed tbrir bead per atoge fi lower then that of e comparable vertical-turbine pump. Although single-stage pumps predomi*te, two stages ar often used sod ometlmes three stages are required to heads below the range of a verUcal-turblne pump. They ore usually "Had wet-pit propeller pumps and .lTC aither axial-flow or mixed-flow TMPllm. 8*-fn whet tereicet ere verticalpump* usedf ^""^tBping from wefle constitutes largest field ol applications, but 1 2Motor4rlven, yertleal-ahaft, dif fuser, multistage, dcepwell eon- Vertical-shaft turbine dcepwell pump has discharge opening above trlfugal pump has pumping element ,the foundation and driving shaft on- suspended from (he discharge piping closed in a tube and oil lubricated 'owe* . January 1948 (41) 105 m