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IEIeetrkol-energy requirement* run hcovler, relatively, then their peak In winter. As o result, plant need! both condensteam during. summer and fall but, nevertheless, rooch sing end noneondensino turbine generators ter best economy * .4 * Reliability, Continuity Mark Institutional Plant Complete gamut of power services--electrical energy, steam, compressed air, hot and cold softened water--features the modern institutional power plant so that failure of power* (house equipment proves costly and dangerous tylJ NEUBAUER, Ukrbe 4 Co. St. Paul, Minn. 6 flow diagram pictures the distribution of steam at the various pressure levels, tndicotei flexibility. balance ihoi turbine exhaust and reducing stations glvo Services, operation, ecoaotny, re* liability end equipment layout, almost in that order, dictate institutional power* plant design. When the Rochester, Minn. State Hospital come in lor expension to serve an eventual 3000 pa tients, the first phase included e new power plant. Besides straightforward planning for final conditions, the new operating features had to permit eco nomical interim power services. These services include steam at dif ferent pressures. Fig. 6, electrical en ergy, cold end hot softened water, compressed air. There was immediate need for 40-psig steam for sterilizers ond at lower pressure for heating nearly oil buildings, including those in the first expansion. So we chose 50-psig steam for distribution to buildings, then specified local reducing stations to drop this pressure for heating systems. On top of this general steam demand was o special 100 psig (or laundry mangles, presses, other equipment. Electriool-energy needs include ac and dc. Dc in laundry and kitchen is only temporary, slated for eventual ac operation. To generate this energy we needed steam at considerably higher pressure than our 100-pslg top process need. So we selected 270 psig for our generating level, and hence our steam- boiler output. Boiler Selection. We pieked two 30,00(Mb*perhr 270-psig 750-F steam generators, Fig. 2, to meet above steam needs. These units of 2idrum, bent; tube design now firing natural gas (and oil H needed) hove their water- go CNOtNCEttNO AND MANAGEMENT,SECTION ROWE* 2 Two selected boilers, 30,000 lb per hr, 270 psig, 750 F, A High-pressure steam from boilers enters a manifold for hove hung up 79.5% efficiency burning naturoi-gos fuel. V distribution t0 power-.penerotors, pressure-reducing units 5 Cooling tower, Induced-draft-fan type, cools woter for condensing unit, /eft will furnaces, forced- and induced-draft ftns suiloblo (or coal-firing on a travelIng-grale spreader stoker should this equipment ever be needed. Three combination oil-and-gas burn ers mount in a triangle on front well of each boiler furnace. Natural gas from mid-continent fields reaches the plant at 25-40 psig, drops to 12 psig at gatregulating house. Then as gas reaches eich boiler its pressure dropa still more through a regulating valve operated by combustion-control equipment. Boil ers develop full-raled capoeity with gasburner pressure of 7 psig. Only fuel is natural gas except in winter when the outdoors stays under 5 below zero. During this cold weather, fuel Is No. 6 oil, stored in four 15,000-gal under ground tanks some 75 ft from the boiler room. One motor- and one steam-driven pump, an oil heater, piping and acces sories ere all assembled on a common bedplate to deliver this oil from storage to the combination burners. These burn ers each carry a gas pilot fed from the domestic goo, making them aofe from any service interruption. Oilburner elements employ 's wide-range mechanical otomizing design, handle oil at 275 psig, 210 F. Tubular oir preheaters furnish com bustion air to the burners at lop temp erature ol 335 F and corresponding minimum flue-gas temperature of 305 F. We have to use on auxiliary duct to bypass some combustion air to the sir preheater outlet at low steam-generator loads so flue-gas temperatures do not get below the acceptable 305 F. A temperature regulator operates a damp er to, give an automatic control over tbe amount of bypassed combustion air. A motor-driven forced-draft fao with inlet vane dampers controls combustion air. The induced-draft fen ties into a venturi etaek that projects 12 ft above boiler-room roof. A steam turbine drives this (on through a reduction gear. A diaphragm valvo in the steam-supply tine picks up swings in steaming rates, sets off .the proper accompanying changes in i-d (on speed. Turbina-Oenerators. The 270-pilg ?SO- Mr i tsi ENOINEEBINO AND MANAGEMENT SECTION I