Document p2RkoeG3w2db9oMEyknXVVxpX

DEAERATING HEATER continued down flash section posset through the second tier of troys on the first leg of its cross-counterflow with respect to makeup water. The third tier then de livers only pure uocontamlnnted steam. Fig. 2, to the downcoming deaeroted water streams. An ejrtemahdesign vent condenser*-- steel shell with admiralty B metal tubes --was selected since it con`provide pure condensate for feed pump seals. Blowdown Questions. Up to 35% of the 200,000-lb-per-hr boiler output, or 70,000 lb per hr, esn go to blowdown snd this' flaahes directly into the heater In a separate flashing compartment to ovoid long, large steam pipes and large flash tanks. An exchanger oltached to the heater shell, Fig. 2, cools the blow down liquid drains while a (team sep arator within the flash chamber dries the recovered steam and passes H to the seoond of the three tiers of trays In the deaerator section. Selected volume of deaerated-wster storage is In line with operating expe rience at other similar plants. Npih requirements prompted rather special considerations. The standard approach involves elevating the healer storage compartment above the boiler feed pump to where it has enough head to avoid flashing in normal operation. A second choice resorts to subcooling or chilling the deaerated water below the control pressure temperature relation ship after it leaves the deaerator on Its way to ths pump, located at substantially BTode elevation with the heater storagetank outlet. Two snbcoolers went Into this design equinoed with controls to reduce water conditions from 916 to 296 F at 20 psl. One of these coolers takes Inlet water as a coolant The second draws on an emergency source that au tomatically enters the secondary sub cooler if the deaerated water tempera ture gets above a preset, danger limit- Absolute economy in stcam-conden* sing capacity in this instance had to go by the boards. Each heater, weighing 50,000-60,000 lb empty, plus piping, would have to be hoisted 50 ft in the air to provide flooded boiler-feed-pump suction. Obvious Costs were further ag gravated by a need for piling work In the low bearing soils of the area. .The arrangement of Fig. 2 gave immediate savings of about f50,000. This problem of assured boiler-feed pump suction at all times Is s severe one at higher pressures. And it be comes particularly so when lorge quan tities of deaerated water are In equi librium with high-pressure steam. A sudden loss of steam pressure and a large-scale steam-flashing occurs, bind ing the feed pnmp so seising and costly pump damage result. (Internal flash preventers in the heater-storage com partment is a preferred solution to this problem.) CTEEl MIllS Quite o different set of conditions prevailed when a 1,000,000-lb-per-hr 2sprsy deaerating heater went into a Midwestern steel mill as a follow-up for a 1,000,000-lh-ocr-hr hot-orocess hotxeolite plant for 650-psia boilers. Ptant load fluctuates as hich as 259b at in frequent intervals but each time load swing lasts from 5 to 10 minutes. Nor mal makeup runs somewhat less than 750.000 lb per hr. Here is the picture the steel mill pre sente, Fig. 3. Incoming cold water h city mains posses through on e*n tubular vent condenser with a top v peraiure rise of 20 F at maximum }1 It then sprays through a rosette' spring-loaded, self-adjusting, g tpray valves in a Sphetieoae hot-pi unit. This heats water to within sT steam operating conditions of 227 p 5 pslg, and removes over 95% of condensable gases in (he water. The now-heated raw water under u partial softening and ailiea reduction^ 2 ppm with dolomilic lime. Precipf ' separate out In a sludge bed ieati low upward rising rates that are tinuolly decreasing to o minimum'! 2.1 gpm per sq ft at the 1,000,000-ft? per-hr toad. Effluent from this sphod cone hot-process softener contains [J than 5-ppm turbidity. It proceeds tatjj a battery of six 10-ft-dia by 5-ft strsl|kj double-decked, hot, styrene-zeolite ta^l eners where it is softened to zero hardJ ness. When the water leaves this itsgj it is ready for deaerated healer proeeil Ing and storage. There were three possible arrtnp ments, Fig. 4: Scheme A--thoronghfj hookup, providing maxljnum flow atW pressure of S psig in both healer sal softener. Scheme B--stepwise hooks)! of heater at 40 pslg and softener it I psig, renulring a separate, additional,' 40-psig healer raising equipment b-] vestment end operating costs. Schcat, C--vent condenser assembly emolorfaj[ an external tubular design on the dt] aerator for top temperature rise of 20 F on Incoming water, followed by a vs condenser on the hot-nrocess softest* for on extra 20-*1 plckuo. This pm (Continued on page 198) -i , -Design Characteristics of Modem Oeaerating Heater- Tr* Crfm (low Psratkl, Counter dpfhcrcaOtlrrl, eooitir U-lubt tr itralftit (lows In two-etage steps. PsralkJ lUsw Countercurrent Hows to twoiti|t step*. Atomisation In aeeond stage. Amt BeU'ftdJusting spray valves (wttb imr valves these tray hcatera are eoray-tray type) ytssd ertftccs In dlsirlbutioa pipe. fMMtlng. vilir ditlrlbulbn V-netctied ectr boi plus distribution pans and trays. 71*ed orifleo in pipes pics distribution pans nd tray* Spray valves and distribution paa Wr(-(( Saoond- 5r*am- vafar (Up prassur* Eiaa/faf dMfritton drop, ps/ Heater . trayv 8(ny Trsyt O.I-OJ SelT-sdJustIng pray valves, ftisd oriAcas Inplpa Weir dbtributv--t-t Bpray valves --SO vised erlfim --fl.M* 8ame as ihort 8pry valves Bteon-Jet 0,5-1,0 atamlcstlon with And or rariaWa-area ENOINEERINO ANO MANAOEMENT' SECTION rows WM UIU. ewi MA ' end . . j f WHITE, PmWeM .jketf fogiowho Corp When this teel plant found HiaV iteam capacity for half ihsir procetcing needs would b* condemned, they swung in to action fait. Smart engineer ing' located and moved a big straight-tube boiler tome 500 miles to - - COMBINATION BURNERS In final Installation use notural qbs, coke pox. fuel oil Replace 100,000 Lb per Hr in 17 Wk UtKNCQUA Woakjs of Colorado Fuel nd Iran Corp processes about 600,000 tens ol steel, neorly 50% of total capscliy, through a blooming mill driven by 15,000-hp Mcloiosh-HemphSII replace the capacity just condemned. J F White Engineering Corp, of Den ver, was then completing inltallatlon of a 15,000-kw turbine-generator in the mill power plant. Engineers from While steam engine. Up to 1951, 15 Stirling joined forces with CF&l men to develop ^bcllm, installed about 1906 in East q plan for Installing 100,000 lb per hr Mill plant, generated ateam (or this en of used-boiler capacity. This would re gine and other small mill processes. The lieve the immediate shortage. Also, Mooning engine exhausts to atmo . CF&l ordered two new 100,000 lb-persphere, so the boilers operate on 100% hr units to modernise both East Mill hot-process-softened makeup water. and B plants. During routine semiannual inspection Replacement Unit. Within two days ta 1951, the insurance company's engi after CF&I learned East Mill boilers neers discovered o serious Increase in would be condemned they asked White iatercrystalline cracks in No. 8 boiler's engineers to canvass the U.S. power in Ueao drum. There were cracks as long dustry for an available unit. In the idle * 54 In., extending halfway through Sinclair Refinery at Coflcyvllle, Kan., . drum shells on eight ol (hp.13-oper they located a Walsb-Weidner sectional- ating boilers. The insurance company lieader boiler, with waierwalls and Foi- *ould not issue any insuronen for aix icr-Whecler superheater. Alter obtain nnila, and only conditional insurance ing National Hoard inspection under w temporary operation of the other ASMS Boiler Code, they secured an two boilers.wiih cracks. option to buy this unit- It proved most The mill was faced with both imme- - suitable because: ***** loss of substantial rolling capacity (1) It could be dismantled immedi nd increased heating demonda during, ately. (2) Straight-tube construction tnespproaching winter. CF&l engineers was most adaptable for rapid disman diverted steam from B plant, on the tling and reassembling. (3) It had a * *We of the mill, and started In- large furnace volume, os it was de MNe* for. the fastest possible way to signed to bum acid sludge. (4) Super- -healer surface could be reused as an economizer. (5) It could he shipped in less than five days since it' was on a branch of the AT&SF Railway, would require only one yard switching. (6) Inspectors had found it in virtually "at new" condition. On Nov 6, 1951, CF&I accepted a lump-sum offer for engineering, design, dismantling, moving and re-crccting the boiler, complete with pipirfg and aux iliaries. White personnel started dis mantling operations the following day on o schedule of 9-hr days, 6-day weeks. Table I summarizes progress.- Before dismantling, White engineers marked pieces and checked controlling dimensions for re-erection. By carefully studying the construction, they found several procedures that saved consider able time in re-erection. Principally, they moved sectional headers and con nected tubes as units. They field-cut the two connecting feeder and releaser lubes and a nipple to the mud drum. They cut waierwalls through the headers to fit railway clearances, and shipped the headers as units. Drawing si bottom of page 82 allows unit's arrangement, with arrows indicating tube cuts and field welds. Welders qualified under Section UlUAiY 1933 ENGINEEBINO ANO MANAGEMENT SECTION 01