Opening Paragraphs:
 The Bangor Hydro-Electric Co has recently completed the installation of the first regenerative type of gas turbine unit to go into central station service in this country. Operation of the unit was begun on Oct. 30, 1950.
Increased over-all efficiency is expected from the installation in comparison with non-regenerative equipment. This is due to utilization of a substantial part of the residual heat in the turbine exhaust to preheat the compressed air before it enters the combustion chambers. 
Article written by Paul F. Kruse, who was the Chief Engineer of the Bangor Hydro-Electric Company.  Article is reprinted from the January 1, 1951, issue of Electrical World, produced by General Electric Company.https://digicom.bpl.lib.me.us/bangorhydro_news/1061/thumbnail.jp

Bangor Hydro-Electric Company

Kruse, Paul F.

English

Bangor Community: Digital Commons@bpl

Bangor Public LibraryBangor Community: Digital Commons@bplBangor Hydro Electric News Bangor Hydro Electric Company1951Bangor Hydro-Electric Company RegenerativeType Gas Turbine InstalledBangor Hydro-Electric CompanyPaul F. KruseFollow this and additional works at: https://digicom.bpl.lib.me.us/bangorhydro_newsFIG 1-REGENERATIVE GAS TURBINE of 5,000-kw rating in one level. Turbine, compressors and combustors are between compact arrangement has intercoolers and regenerators on twin regenerators. Estimated cost is under $200 per kw Regenerative Gas Turbine Efficiently Supplements Hydro Bangor utility selects first of regenerative type gas turbines for its new Edward M. Graham station to provide standby and peak back-up for hydro in conjunction with diesel capacity PAUL F. KRUSE, Chief Engineer Bangor Hydro-Electric Co, Bangor, Maine The Bangor Hydro-Electric Co has recently completed the installation of the first regenerative type of gas turbine unit to go into central station service in this country. Operation of the unit was begun on Oct. 30, 1950. Increased over-all efficiency is ex-pected from the installation in com-parison with non-regenerative equip-ment. This is due to utilization of a substantial part of the residual heat in the turbine exhaust to preheat the compressed air before it enters the combustion chambers. The initial unit (Fig 1) is rated at 5,000 kw by the manufacturer, but the expected maxi-mum output at 70 Fis 6,000 kw. The machine was ordered in Octo-ber, 1948. A new brick and steel ;tructure (Fig 2) will house this first unit and provide space for a second of like design.' The new plant com-prises the Edward M. Graham gen-erating station, oil storage tank, cool-ing water intake, substation and in-terconnecting transmission facilities. All-Hydro Genernti~n lnadeq1111te ••• Decision to purchase the gas turbine culminated a long series of studies by the company's engineering staff. The company serves east central Maine, reaching about 100 commun-ities having an estimated population of about 145,000. Before December 1948, all system generation was hydroelectric. There are 11 hydro plants aggregating 39,-570 kw effective capacity under nor-mal water conditions. In 1948 three Reprinted from ELECTRICAL WORLD e January 1, 19~1 2,000-kw diesel plants were installed. With the new gas turbine at Veazie the capacity of the thermal ·units will reach 12,000 kw, bringing total gen-erating capacity to 51,570 kw. In-dividual hydro plants range in ca-pacity from 320 to 9,300 kw. Normal heads range from 17 to 60 ft. Ten of the hydros are of the run-of-river type, operating under heads of 14 to 25 ft. Many of the company's plants have the benefit of controlled storage on the princi?al branches of the Penob-scot River totaling about 61. 5 billion cu ft. Additional storage of about 6 billion cu ft is available elsewhere. Studies by the Bangor company initiated as far back as 1937 weighed the relative economy of a steam tur-bine generating plant and further hydro development. Considering the power and process steam requirements of a paper mill customer it appeared that customer installation of a new boiler plant and high-pressure steam turbine installation would provide lower cost energy. .. ~han any other type o~ plant then investigated, including undeveloped water power sites. It was HEAT BALANCE DIAGRAM FOR 5,000-KW GAS TURBINE POWER PLANT At 1,000 ff above sea level H11;h·pressure compressor -High-pressure / turbine .,,.. I Woferin : 347F, l,500F- _ comb11>fors ?OF. 800 j 95 F 1286 psio - -- 64,840,(XJOBfu/hr qpm,13,842,- 4146psio 9398fu/hr mler - Regenerator cooler ~;:::::::::;:::::::;::==~~ Exhaust out ' Woferouf · 475F.!411ps10 104 7 F :J 25,n1,310Btu4v • 3,840/XJ08fw1rr (latent heat) 316F. 42.17 psio Air in:BOF, 141/psio, 12 lb/sec Low-pressure /ur/)lnf! ~lb/hr No6 fuel otl Bearing. qeor, generator ond accessory losses 1,873,131 Btu/hr Miscellaneous losses 2,92"1;0/4 Btu/hr flG 2-SIMPLE BUILDING of brick and steel adjacent to sub-stations houses gas turbine with space for second unit FIG 3-HEAT BALANCE diagram shows 17,065,000 Btu per hour output from 64,840,000 input in content of Ho. 6 fuel oil also determined that the development of further increments of capacity at the company's existing run of river plants at Veazie and Milford, together with increased capacity at the Ells-worth hydro station could be done at comparably low cost. This held new capital investment to a minimum. Operating costs at the existing plants were not materially increased by the new capacity. This policy was adopted, and between 1938 and 1943 8,500 kw in hydro units were installed. When the new steam plant of the paper company went into service (see Fig 4) in the fall of 1947, its effect was to release about 10,000 kw of the utility's generating capacity for sup-plying the demands of other types of load and for meeting postwar growth. Jn so far as area power requirements are concerned this was the equivalent of a 10,000-kw addition by the power company itself. Diesel Un:ts Bou~ht •.• Immec11ately following World War II the Bangor company experienced the same ac-celerated growth of domestic and other firm types of load as did other parts of the country. Coincident with this rapid rate of growth there began in July 1947 and extending to No-vember 1949 a drought unequalled in any similar recorded period. It was clearly apparent that to guarantee con-tinuous service to this firm type of load, thermal capacity was required on the system to back up the com-2 55 50 • .. l 45 J .. 40 .! 0 ! 35 O> c ! • 30 J ,, c 25 0 .. ~ 20 1 l Ci 15 .. c c c 10 5 ---·--· L.-/ / ! '~~ : o----t-r-_7 'fo1_2 I J : V tndu~friol I .,, / Pop11r ,Mill food ~I~ I 1)1 ... l----1-----11-----t~y--T---+,.,_--+---+----r-~g-t---~ .o. '-.I / ~1~ I ~~ ~~ : ::t:, Dom11sfic, co •m11rcio ond oth11r firm foods I I I I I I I l : I I I I t 1936 It» 9!MO 1942 844 194& 1948 1950 1952 'feol'• FIG 4--TOTAL LOAD encroached on generating capacity until 10,000 kw was recovered for postwar growth when paper mill installed its own plant FIG 5-SYSTEM GENERATION PLOT discloses significance of pa'per mill load that was relinquished i1t 1947 pany's hydros. The character of a part of the load was changing. Whereas tormerly a substantial part of the company's generating capacity (Fig 5) was used to serve a paper mi.II load on the basis of secondary power subject to curtailment under adverse conditions if and when necessary, that type of load was now to be replaced by firm load requiring continuous service. The result was that the com-pany could no longer rely solely on available hydro generation. For the first step of thermal · ca-pacity three diesel plants were built, each having two 1,000-kw, 4-cycle, 1,425-hp engines. These were par-ticularly useful in two locations in pro-tecting service to fish packing plants and improving regulation on long transmission lines. Gas Turbine Unit Selected ••• Early in 1948 President E. M. Graham de-cided, as a result of continued studies by the engineering department, that the next unit of generating capacity to be added to the system should be a thermal unit of not less than 5,000 kw. The development of the art of gas turbine manufacwre had pro-gressed to a point where the builder of the machine could guarantee equal or better economy in performance of such a unit than with a steam· unit of comparable size. Tests were in prog-ress at the time in the factory on a simple or single stage of gas turbine which indicated success in its per-formance beyond any reasonable doubt. Designs for the regenerative FIG 6-HYDRO AVAILABILITY under both high and low water indicates value of gas turbine and diesel increments type of unit (Fig 3) had also pro-gressed to the point where it was ready for commercial manufacture. Although the gas turbine type 01 unit lacks the experience which the steam turbine and diesel types have had, it was deemed more advantage-ous than either steam or diesel> in every other respect for the next step of generating capacity to supplement the company's hydro system. This conclusion· was based on the follow-ing advantages of the gas turbine plant: 1. Its capital cost is estimated to be less than that of a steam plant of com-parable size in this locality and when completed, with two units installed, is expected to be less than $200 per kw. 2. The power plant building and permanent structures are simple in character and less expensive than those of the steam plant. 3. The water requirement for cool-ing purposes is only from one-fourth to one-sixth that required for con-densing purposes in a comparable steam plant. This factor was a major consideration in the location of a thermal plant in the vicinity of Ban-gor. 4. The thermal efficiency of the re-generative type of gas turbine unit is expected to be equal to or greater than that of a comparable steam unit. 5. The gas turbine will burn Bunker C or No. 6 oil, whereas diesel units require a lighter and more expensive oil. At present writing, th"e pricer of Bunker C oil is about two-thirds that of premium diesel fuel in Bangor. 6. The gas turt>i!1e unit may be placed on the line from cold condi-tions upon 30 minutes' notice. It does not require burning of fuel when out of service, as is the case of a steam plant where fires are banked and fuel is wasted ·in order to maintain the unit in a condition to be placed on the line in a reasonable time. This factor is -of considerable importance to the Bangor company, since it is ex-pected that the gas turbine plant will operate at a light Ioad-factbr -on the peak of the load. 7. The gas turbine plant does not require highly specialized operating personnel and the number of attend-ants is expected to be less than would be required in a steam plant. This advantage should reflect substantial economy in operating costs. 8. The maintenance charges on the gas turbine installation are expected to be no greater and possibly may be less than those of either steam or diesel units of comparable capacity. This is due to the comparative sim-plicity and relatively small number of component elements of the gas tur-bine. The accompanying chart (Fig 6) in-dicates the manner in which the ther-mal plants are expected to be oper-ated to supplement the company's sys-tem of hydro plants. Fig 6 shows the prime capacity of the so-called run-of-river plants on ~he system to be about 21,200 kw. With the Ellsworth storage plant the system has a prime hydro capacity of 30,500 kw. The capacity of the run-of-river plants is affected not only by low water but also by reduced head in time of high water. Thus, with hydro operating conditions represented as existing 50% of the time, fl.ow in the Penobscot River at Veazie is about 9,000 cfs and the operating head 17 ft. Under that condition the only limitation on output is the installed generating capacity of the plant. For the low-water-supply operating condition (Fig 6) wherein the fl.ow at Veazie is 4,700 cfs for approxi-mately 5% of the time, the plant out-put is reduced because of insufficient water to supply all the installed ca-pacity. In high water periods usually occurring in the spring, the plant out-put is curtailed by a reduction in head caused by lowering the 'fiashboards on the dams and raising of tailwater 3 3-51 (500) 7-61 (500) 440 r levels. For the condition indicated at Point C the flow at Veazie is about 49,000 cfs ~nd the operating bead for that flo,w __is !\pprmtjmately 13 ft. The gi:p.erl!ti~g capacity indicated for the atqres~.~ Jµni~g flow conditions is cqnsidered as prime capacity because of con~i.derable diversity of flow con-ditions throughout the system and be-cause the river flow at Veazie rarely exceeds those limits during the aanual peak load period, usually occurring in December. To meet the projected 1952 peak load of firm power customers witla adverse water conditions wherein only the prime capacity of the hydro sys-tem is assumed to be available, the gas turbine plant is expected to oper-ate on a daily load factor of not over 25%. This indicates the stand-by or peak load type of operation expected of the new plant, and because of the simplicity of its operation emphasizes its value to the Bangor system as com-pared to a stellm unit. It is furthermore expected that as load continues to grow, further hydro capacity will be added to the system so that in the years to come hydro and thermal capacity will keep pace in such a ratio as to afford the most economical over-all system operation. GENERAL. ELECTRIC S C H E N E C T A D Y, N. Y. 

Bangor Hydro-Electric Company Regenerative Type Gas Turbine Installed

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Bangor Hydro-Electric Company Regenerative Type Gas Turbine Installed

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