Document Jre20zMEb3X35q35L9VVmdOEe

CONSIDER H-T WATER continued High-Temperature Water li Adaptable to Many Different Industrial and Commercial Uses in Process and Healing . .-L.i-' * . i' nlr> ipoee heating, flow temperature depends on outdoor oir temperature 'i'. *. -i.'1 ;n Where large quonmm at domestic woter are needed you eon use a hooter like this Instead ol the unit shown in Fig. 3. Efficiency of theso units is good water into steam space, through the re turn mein, Trays break it into a fine spray and leaving water has same tem perature as saturated steam used for heating. Direct contact provides high heat-transfer efficiency. Circulating pump is placed far enough below heater to obtain sufficient head to prevent steam flnshing and wator ham mer in the lines. For large capacities, direct contact heaters may he mounted on horiionts) expansion tanks in the form of domes, Fig. 4. Using cascade heaters you can gen erate h-t woter at any point in a steam plant. This-makes them feasible for jobs like new space healing or for re placing worn-out steam systems. Ileaicr needs only smell floor area and can he located in production spaces, if neces sary. No more maintenance is'needed than with other typea of heat ex changers in usual power-plant service. Heal -Storage. Heat consumption in most plants varies throughout ihe day. In steam-heating systems, variation of heat consumption changes boiler pres sure, and boiler bring rate must be varied with load changes. In h-t water systems the large volume of water per mits changes in heat demand without appreciable variation of boiler pressure. Boiler efficiency is higher become firing rate is more even. Increase li-t water system capacity by connecting boilers in series, Fig. 8. Of the three boilers shown, No. 1 is the so-caffed steam boiler, No. 2 and 3 are filled with water. All boilers can be fired at the same lime, hut No. 2 and 3 must hove o lower rale than No. ]. Properly designed h-t water systems generally have enough spare enpneily to meet fluctuations in heal demand. An extra accumulator is needed only in sys tems where power and beat peaks do not coincide, and exhaust or bleed steam ,, used for woter heating. The satne'i^ true of systems having boilers that tn shut down during the night and tfiyt have a high peak load in morning. s` H-t water accumulators are simpV,' ond more effective than steam type ^ cause the latter run at varying pressure? Also, storage tanks for h-t water a'tt much smaller than those for steam tjj'. terns with the same heat-storage eapicf ity. Cylindrical tanks with dished beadp make suitable h-t woter accumulators* They may he placed outdoors, if desired* Piping. Fig. 6 shows one way of hook-d ing up an accumulator. During ehsr^l ing, h-t water enters accumulator top! at 320 F, It pushes cooler 220-F wile/ from accumulator bottom to the cascade heater. During discharge, hot water u1 taken from accumulator top white cooled water returning from system enters thel Imitom. -.f A narrow layer about I ft deep sert nroies the high-temperature water from] the low-temperature woter below it andij eliminates mixing or turbulence of water in the accumulator. Regulating vslni' for charge and discharge are usuaDy>j operated by hand because peak-W! periods are ihurt. But an automatic]! regulator may also be used as is showir in Fig. 6. Tubular Heaters. Fig. 9 shows hewij a heater of this type is used tu replace a boiler in a low-temperature hot-wateri heating system. In Fig. 10 o h-t water? heater generates steam for process <4 other uses. Be sure temperature of Ivil water is higher than that of steam to be" generated. ' v'* Temperature Control. For space hello ing. system output Is a function of out door temperature. The lower the out-: door temperature, the more heat needed:; Since heoting plants are designed fori specific low outdoor temperature, nut-^ put must be controlled on warmer dayrto avoid overheating. Many different temperature rcguli7'} tors may be used for steam-heating ey\j terns but In water-heating systems indoor^ temperature is varied by changing thd[: temperature of the water being circu lated. Amount of vorietinn, in turn, d?\ pends on the outdoor temperature it the time. -i In h-l water systems, temperature ii-t regulated at s central location. Bypotijj and mixing valve regulate temperature? of leaving wnler so it is suitable for ^ heoting needed. Chart, Fig. II, can be'* prepared for a given plant to simplify]; figuring of best water temperatures. .} Return water is bypassed either msfl-.t uatly or by an automatic ratio controller-." Most plants in Europe use manual by-^j passes except lor some process heotinf'l where 3-wny ratio controllers are used. ENGINEERING AND MANAGEMENT SECTION FOWf* f DATA SHEET., Alloy Steel Pipe--ASTM Specification A-31J (1 Cr, Zi Moly) -- r -r a*. u TTml o, 1 ,, 1 h 1 1 * 1 * 1 " 7miTii.n 1 u.its 1-u.w* l \\m\ MW l less 1 m | Rl. If. U. | If. WW4 .l in I >u I ~sw I ns I tP- I iT iV.,to* 1 n.isol n.iwl nos I uw Maximum Allowable Working Pressure--6 Henc's the last in the series of six data sheets to speed up selecting correct pipe sixes. No. 1 appeared in July, and No. 2 to 5 in September to December 1952, respectively. These tobies help avoid calculation errors In addition to saving time. All tables ore based on allowable stresses published >n August 1951 issue of Mechenicol Engineering and the p/s values given in Crane Co catalog No. 49. By Ckohce C IIalxel Beuon, Most. Alt reproduction rights reserved by the author lO POWER