"ENERGY STUDY OF A GAS-FIRED TURBO-GENERATOR"

Transcription

1 Engineering Jornal of Qatar University, Vol, 1, "ENERGY STUDY OF A GAS-FIRED TURBO-GENERATOR" By M.R.S. Okelah, Assistant Professor, Faclty of Engineering, Qatar University, Doha, Qatar, Arabian Glf. ABSTRACT As far as energy tilization is concerned, the performance of a gas trbine-generator combination, depends on some key factors among which are; engine featres, methods of tilizing heat energy associated with exhast gases, fel characteristics, variations in ambient conditions and variation of electric load. The present work is intended to evalate specific heat consmption and specific fel consmption of a 44 MW trbo-generator nit, at Ras Ab-Fontas Power and Water Station, in view of likely changes in ambient conditions of Qatar. The stdy also covers the effect of load changes on specific heat consmption and component efficiencies. The method sed for performance evalation is herein explained; necessary on-site measrements are identified and procedres sed in the analysis are otlined. Validation of reslts is confirmed throgh comparison between calclated trbine inlet temperatres and measred vales. Excellent agreement between these temperatre vales is shown to exist. Cases of energy loss are also discssed. 1. INTRODUCTION Ras Ab-Fontas Power and Water Station is now the primary sorce of electrical power and potable water in Qatar. Started in 1972 and completed in early 1984, it is one of the largest installations of its type in the world (1). The final configration of Ras Ab-Fontas comprises twelve gas trbine generatornits and two black-start gas 115

2 Energy Stdy of a Gas-Fired Trbo-Generator trbines with a total rating of 622 MW. which is eqivalent to total ISO rating of 965 MW. The performance of sch a plant, as far as energy consmption is concerned, depends on a nmber of factors. One basic factor thereof is the design featre of the gas trbine-generator nits, which in trn depends mainly on compressor pressre ratio, maximm cycle temperatre (Trbine Inlet Temperatre) and engine component efficiencies. A second factor is the method of tilizing heat energy associated with exhast gases. Once the engine is installed on site these two factors are fixed. A third basic factor is the variation of ambient conditions, temperatre, pressre, hmidity ratio and dst content. Among these, temperatre is the most inflencial factor affecting the thermodynamic performance of the engine. Generator loading has also remarkable effects on engine performance. There are some other important factors that shold be taken into consideration in an energy stdy sch as: availability of fel, its characteristics and price. The present stdy evalates engine performance and energy consmption of a selected gas trbine nit in view of those factors which are likely to vary dring operation of the trbo-generator nit. 2. DESCRIPTION OF PLANT The twelve large gas trbine-generators are hosed longitdinally one after the other in a trbine bilding of 722 m in length. Along the front of the bilding, on the eastern side, are the air intake strctres, the waste heat boilers with the by-pass stacks and the desalination plants. Local control stations, the electric switchgear and the transformers are arranged in the western side. A view of the plant is shown in Fig. (1). Among the twelve gas trbine-generator nits, six are manfactred by Kraftwerk Union AG (KWU), and are of the V.93 type. The other six nits are manfactred by Mitsbishi Heavy Indstries Ltd. (MHI), and are of the MW 71G type. They all operate in base-load mode, with filtered air intakes. The first two KWU gas trbines, spplied for the initial installation, operate at trbine inlet temperatres of approximately 82C at base load and at approximately 85C at peak load. These vales were increased to approximately 85C and 87C for the for KWU gas trbines installed in the second extension of the plant. The gas trbine-generator (trbo-generator) nit considered in the present stdy is one of the two KWU nits in the initial installation: it is identified as nit GT.2 in the power station. Exhast gases from each KWU trbine, at a temperatre of 44C, are sed to generate satrated-steam flow of Mg/hr in the scceeding forced- 116

3 M.R.S. Okelah circlation drm type boiler. This rate is increased to 16 Mglhr with the aid of additional gas brners. The steam pressre is 14 bar. The feed water is deaerated at a temperatre of 14C and the temperatre of the retrn flow from the desalination plant is 9C. In addition, the plant has for axiliary boilers at hand, each capable of prodcing satrated steam of 8 Mg/hr; these can be connected to the desalination plant even if the gas trbines are not operating. Gas trbines ths provide mechanical power for generation of electricity, which is the primary prodct of the plant. Moreover, heat rejected from trbines is sed to generate steam for prodction of potable water, this being considered a by-prodct of the plant. One conseqence of sch an arrangement is that the heat tilization efficiency of the whole plant improves sbstantially, while the thermal efficiency of the gas trbine becomes not as important as in the case of gas trbines entirely devoted to the prodction of electricity. 3. GENERAL DESIGN FEATURES OF GAS TURBINE UNIT GT.2 KWU gas trbines are single-shaft machines of standard design. They are sitable for driving generators in base-load and peak-load plants. They can be sed in combined gas-steam cycles, also for provision of district heating. They can bm liqid fels sch as light or heavy fel oils as well as gaseos fels sch as natral gas or blast-frnace gas. The compressor and trbine, the principal components of a single-casing single-shaft gas trbine, have a common rotor. It is spported in only two jornal bearings and located by a single thrst bearing, all of which are located otside the hot pressre area of the machine. The trbine rotor is internally cooled. A small percentage of the compressed air is bled off from the main flow at the end of the diffser and is admitted to the interior of the rotor throgh holes in the centre hollow shaft. Air is distribted between trbine discs and is directed to blade root fixings. It discharges thereafter into the hot gas flow ths providing a cooling film over the blade roots in the process. Two identical combstion chambers are arranged vertically on either side of the trbine and are connected to side flanges on the trbine casing. This design provides short and concentric gas and air paths from compressor to combstion chambers and from chambers to trbine, ths involving minimm flow losses (3). A cross-sectional view of a typical gas trbine engine is reprodced in Figre(2). 117

4 Energy Stdy of a Gas-Fi,.d Trbo Gtnorator Fig. 1: A View of Ras Abo Footas Power and Water St tion (Adapted from referen ~e ( 2)) Fig. 2: The KWU, V.93 Type, Gas Trbine Engine (Adapted from reference Q}). U8

5 at 1 Air 1 Intake l 1 I I f r Fel I v :---_.( ) l Combstor I I Heat Recovery Boiler t l ~ Generator Compressor Trbine l l I J Exhast Gases ~ ~ til 1>1"' ~ Fig. 3: A Schematic Representation of a Trbo-Generator Unit Showing Station Nmbering Adopted for the Stdy.

6 Energy Stdv of a Gas-Fired Trbo-Generator 4. EVALUATION OF PERFORMANCE The method of performance analysis sed in this stdy is based on the International Standard ISO "Gas Trbines Acceptance Tests". It shows how mass flow and trbine inlet temperatre of a single-shaft gas trbine can be calclated by means of relatively easily measreable parameters. Mass flow balance, power balance and combstion chamber balance are sed for this prpose. Details of the method are presented in reference (4) and may be smmarized as follows: 4.1 Measrements Reqired The parameters reqired for performance analysis are listed in Table (1) with sbscripts in accordance with station nmbering of Figre (3). In addition to these variables, the following parameters have to be estimated: - Fel lower calorific vale: H, and specific gravity: w - Generator efficiency: n - Combstion chamber efficiency: nb - Mechanical efficiency: nm, or mechanical power losses Table (1): Reqired Measrements for Performance Analysis. Qantity Flid Location a. Temperatre, k Air -Ambient : Ta - Compressor inlet : T1 - Compressor otlet : Tz Gases - Exhast of trbine : T4 Fel - Inlet to combstor Tt b. Pressre, bars Air - Compressor inlet pl - Compressor otlet : Pz Gases - Exhast of trbine : p4 Fel - Inlet to Combstor : pf c. Flow rate, m3fhr Fel - Inlet to Combstor Ot d. Power, KW - - Generator Terminal : Pot o

7 M.R.S. Okelah 4.2 Data Reqired In order to carry ot performance analysis the following data shold be made available: 1. Enthalpy verss temperatre tables for air, 2. Enthalpy verss temperatre tables for combstion gases, 3. Compressor air flow verss ambient temperatre chart, 4. Chart of oxygen content in the prodcts of combstion verss specific fel otpt (or fel-to-air ratio). This data is provided by KWU in reference (4). 4.3 Basic Eqations The following eqations are sed to calclate air mass flow rate ma, enthalpy at trbine inlet h, 3 overall thermal efficiency n, specific heat consmption SHC, specific fel consmption SFC, compressor isentropic efficiency nc and trbine isentropic efficiency n1 m = a mf (nb (H+ hf - hfs) - h ) - P I n 4 ot m h4 - h1 rna h3. = (hz- h1) + m3 no = SHC SFC n = c mf pot nb(h+ hf- hfs) 1 = X 36 nb mf = X 36 Pot T1 (Tz- T1) ( P2)Ea p1 pot1 nm + h4 m3 1 KJ/KW. hr KJ/KW.hr K - 1 a E a K a (1) (2) (3) (4) (5) (6) Ul

8 Energy Stdy of a Gas-Fired Trbo-Generator o -o QJ -ro -:::J ro LJ X ro E '- i/ 8 7 f- I/ :7 I v 7 ov Fig. 5: Calclated Trbine Inlet Temperatre Verss Measred Temperatre. 124

9 M.R.S. Okelah Figre (6) presents a smmary of variations in ambient air temperatre, pressre and relative hmidity in Qatar dring the year 19S4, (6). The total nmber of observations sed in each histogram is S7S4 (24 hors x366 days). The air temperatre varies from S C to 47 C with mean temperatre of 27 C. Pressre varies from.99 bar to 1.26 bar with mean pressre of 1.1 bar. Relative hmidity varies from 5% to 1% with a mean vale of 55%. Of these variables the temperatre is the most inflential factor and therefore it is given the prime consideration. With sch variation in T 3, the engine mass flow varies by abot 14% from its design vale (4). Otpt power and overall efficiency at 4S C air temperatre decrease to 65% anl9%, respectively of their vales at S C air temperatre. These figres may vary from one gas trbine engine to another bt the general trend of variation of mass flow, otpt power and overall efficiency with ambient temperatre remains the same. Reslts of performance analysis of the trbo-generator nit at different air temperatres are shown in Figres (7), (S) and (9). Figre (7) shows overall efficiency o as a fnction of ambient temperatre and otpt power. In this figre, it is extremely important to plot the overall efficiency crves, for fixed power setting, at same maximm cycle temperatre since the latter has the highest impact on overall efficiency. With this factor taken into consideration in prodcing Figre (7), a redction of efficiency, with temperatre increase, of approximately 2% is noted at higher vales of otpt power ( 44 MW), while slight change in efficiency is noted at low otpt power (2 MW). Figres (S) and (9) show variation of compressor isentropic efficiency 11c and trbine isentropic efficiency Dt as fnctions of both ambient temperatre and power otpt. The increase of nc with increase of T a is explained in the next section. 7. EFFECT OF LOADING ON PERFORMANCE OF GAS-GENERATOR COMBINATION Gas trbine engine performance is at its best when the engine is at its design vales. In the present case the engine is designed to operate mainly in a base-load mode. Therefore, a degradation of performance is expected at part load. Figre (7) illstrates this fact by showing the remarkable effect of redcing load on overall efficiency. It is worthwhile discssing the effect of both load variation and ambient s

10 Energy Stdy of a Gas-Fired Trbo-Generator Fig. 6: Freqency Histogram of Annal Poplation of Horly Data for Selected Meteorological Elements (6). JSOO Ill c.. ::::J :I: 1 - c.. Gl.a E ::::J z Air Temperatre 15Q Figre (6) a Ill c.. ::::J :I: - c.. Gl.a E ::::J z mbr Atmospheric Pressre Figre (6) b 126

11 Dr. M. R. S. Okelah Ill '- :::J :I: - '- ll e :::J z so /o Relative Hmidity Figre (6) c ~ F'"" >- c: <II ;:; -... w ~ m L.. Ql > io Tmax = 83 c P=44MW Tmax = 76 c Tmax = 68 c ! 'P=25MW Tmax = P=2MW 1 ~o~ ~35~ ~ ~45 Fig. 7: Effect of Ambient Temperatre on Overall Efficiency of Trbo Generator Unit. 127

12 Energy Stdy of a Gas-Fired Trbo-Generator 85 :::-e P=3SMW >. c:: QJ ;.;::::... UJ - -- P=3MW.--- ~- P:2SMW,,.-,, ~ ~~ L- J Ambient Temperatre T a c Fig. 8: Variation of Compressor Isentropic Efficiency with Otpt Power and Ambient Temperatre. 128

13 M.R.S. Okelah 92 >. c: Ql "i:j... ~ 87t ~~----~~~~~~~ Ql.s. c... ::J..,.. P:3HW P:35HW 82~ ~ L ~ Ambient Temperatre Ta C Fig. 9: Variation of Trbine Isentropic Efficiency with Otpt Power and Ambient Temperatre. 129

14 Energy Stdy of a Gas-Fired Trbo-Generator temperatre variation on the behavior of a single-shaft gas trbine engine driving a generator with the aid of the hypothetical compressor characteristics shown in Figre (1). For fixed generator rotational speed, N and for fixed compressor inlet temperatre, T1o the non-dimensional compressor speed N/ v' maintains its vale irrespective of load variation ( 8 being eqal to T 1 /reference temperatre). Ths the operatingne coincides with a corresponding N/ Ye line c-a-b-, where points c, a and b represent no load, base load and peak load conditions. Figre (1) also shows the contors of constant compressor efficiency ne with De increasing towards design vales. On this chart are sperimposed lines of constant trbine inlet temperatre (or maximm cycle temperatre) Tmax 1, this is shown to increase towards the srge line and also to increase with increasing compressor pressre ratio (P 2 /P 1 ). The effect of part-loading is illstrated in Figre (11)-A. As load decreases, the operating point moves from point a to point a 1 ths reslting in redction of compressor efficiency (n\ < ne) and possibly in small increase in mass flow. More important is the evolved redction in pressre ratio, (P 2 /P 1 ) and maximm cycle temperatre, (T 1 max < Tmax) The redction of these two parameters reslts in sbstantial drop in overall efficiency. A rise of ambient temperatre increases, this casing in effect a shift in the whole operating line to the left as indicated by the dotted line in Figre (11)-B. A large redction of mass flow and pressre ratio is expected with conseqential sbstantial drop of otpt power. Maintaining same maximm cycle temperatre at increased ambient temperatres minimizes, however, the drop of overall efficiency, Figre (7). Increase of compressor efficiency with increase of Ta as noted in Figre (8) can be jstified by observing the compressor characteristics displayed in Figre (11). A rise of Ta moves point (a 1 ), Figre (11)-A, to the left where higher vales of compressor efficiency may be obtained. A combination of increased ambient temperatre along with redced load is the worst that can happen as far as thermodynamic performance is concerned. Point (a) in Figre (1) moves in sch case to point (d), ths reslting in redction of compressor efficiency, overall efficiency and mass flow rate. The effect of load decrease, (with the conseqential decrease in Tmax), on overall efficiency exceeds however, the effect of ambient temperatre increase. This can be observed clearly in Figre (12). 13

15 M.R.S. Okelah 8 : T /T reference S i PIP referen.ce =87c Tmax a Base-Load (Design Point) b Peak - load c No-Load =75c Tmax Lines of Constant 15% ~/{8% Non Dimensional Air flow Rate ( m 1 Iii IS) Fig. 1: Compressor Characteristics (Schematic). 131

16 Energy Stdy of a Gas-Fired Trbo-Generator N/-ie Ta 1 incre es I I infi/6 Fig. 11: Efred of Both Part Loading and Ambient Temperatre on Trbo Generator Performance. 132

17 M.R.S. Okelah.) r r---.,..----,.---~ x,... ~ E F' t:. ~... >- "' c: ~ "' 7 ~ ~. E w ;;; ~ "' "' > I- 1 c :. ~ ::> I- Generator Otpt MW Fig.12: Variation of Both Maximm Cycle Temperatre 3!ld Overall Efficiency of the Trbo-Generator Unit with Power Otpt and Ambient Temperatre. 133

18 Energy Stdy of a Gas-Fired Trbo-Generator 8. SPECIFIC HEAT CONSUMPTION AND SPECIFIC FUEL CONSUMPTION Specific heat consmption SHC, as defined by eqation ( 4), is a measre of efficient tilization of heat energy for prodcing electrical energy, since SHC is inversely proportional to overall efficiency. SHC variation with variations of otpt power and ambient temperatre is shown in Figre (13). Manfactres of gas trbines, sch as KWU, normally provide an estimate of SHC nder different operating conditions, either throgh their technical pblications or throgh some on-site performance tests. The shaded area in Figre (13) represents the manfactrer's garanteed specific heat consmption, (7) corrected for the considered range of ambient temperatres. Comparison between actal SHC and manfactrer's garanteed SHC shows how mch additional energy need to be consmed, in order to prodce same power otpt de to performance degradation. This additional energy may be considered as waste if we are considering the gas trbine-generator nit alone. On considering the gas trbine-generator-waste heat boiler-distiller as a whole, the additional heat energy is not, however, wasted since it is tilized in prodcing sefl steam. Specific fel consmption SFC can be calclated from eqation (5) in kilograms of fel per (KW.hr). Since the primary fel at Ras Ab-Fontas Power and Water Station is natral gas, mostly Khff Gas, then it is more convenient to express SFC in normal m 3 per (MW.hr). The variation of SFC with generator otpt and ambient temperatre is shown in Figre (13), from which it can be seen that operating the trbo-generator nit at lower than 5% of its capacity reqires some 5 to 1 percent extra amont of fel per nit power prodced. 9. DISCUSSION OF ENERGY CONSUMPTION IN LIGHT OF TURBO GENERATOR PERFORMANCE According to the 1984 Electricity Statistical Report (8), Ras Ab Fontas Power and Water Station contribtion in state generated electrical energy was 2,121,588 MW.hr. This is approximately 6% of the total electrical energy generated in Qatar in To generate this amont of electrical energy, most of the 6,71 million standard cbic feet (1,719 million Nm 3 ) of natral gas, consmed by the power station, was brned to drive the gas trbine-generator nits. When dealing with sch hge amonts of fel, every effort shold be made to ensre efficient tilization thereof. Sorces of heat loss shold be stdied careflly in the light of actal performance 134

19 M.R.S. Okelah Ta =31 c Ta = 43 ~..:.c. w ::c Vl c: :;:::. E ::J VI c: w._ 111 Ql ::r: ;c o Ql. Vl 15 L..c 3 :L,., " E z w ll Vl c: :;:::. E ::J VI c: w VI ro L:J "- ::J aj ::J ll \J Ql a. Vl..c :>.::: Manfactre's Garanteed Specific Heat Consmption 1 1~----~----~----L-----L---~~--~~--~ t.o 45 Generator Otpt MW Fig. 13: Variation of Specific Heat Consmption SHC and Specific Fel Consmption SFC with Power Otpt and Ambient Temperatre. 135

20 Energy Stdy of a Gas-Fired Trbo-Generator characteristics. Althogh recognizing that the excess heat energy spplied to gas trbines may be tilized in the waste heat boilers, there is still reason to believe that an increase in specific heat consmption shold be seriosly considered. For one reason, electricity is not only the primary prodct of the plant, bt it is also the most expensive form of energy: the efficient conversion of heat into electricity implies sccessfl operation of the plant. Secondly SHC is a measre of gas trbine performance, and nsal vales of SHC indicate some sort of engine problems that shold be investigated. Excessive specific heat consmptipn can be classified according to its cases into two major parts. The first part is de to engine degradation of performance. This means that with all variables of the cycle set according to manfactrer's recommendations, the engine fails to achieve the expected overall efficiency. Therefore an appropriate remedial action shold be taken based on the reslts of engine diagnosis and inspection. Excessive specific heat consmption de to engine degradation is shown in Figre (14). In the analysis of trbo-generator nit 2, this part of excess energy is approximately 1.7 MJ/KW. hr at fll load. The second part of excessive specific heat consmption is de to engine part loading as indicated in Figre (14), this depending on general load demands, load schedle of the plant, nmber of nits in operation at a time as well as few other factors. Simple calclations of the annal plant factor, based on the rated capacity of the plant and the total electrical energy generated dring 1984 indicate a vale of.4. Althogh this vale appears to be low, it can be jstified if the electrical power system of Qatar as a whole is taken into consideration. The load on an electrical power system is apportioned among the power plants that comprise the system. The generating capability of the system mst be sfficient to meet peak or maximm demand of the year, normally dring the hot smmer, with some reserve generation to provide for possible failre of eqipment and otage for reglar maintenance. The spinning reserve consists of those machines synchronized with the electrical network and ready for loading. In the electrical power system of Qatar, all plants except Ras Ab-Fontas operate as base load plants. On the other hand, Ras Ab-Fontas is the station which adjsts the total otpt power of the system to meet the demand. While six trbo-generator nits may be sfficient to provide the reqired power in winter time, however, the twelve nits mst be in 136

21 M.R.S. Okelah I L.. 25.c. ~.X :l: :X: Vl c::... 2 Cl. E ::I VI c QJ :X:... QJ a.. l/1 ~ \ ~\ ~\ '\\ r'\' ~'-r-..." r--." ~'-", SHC t'-." ~... II,~ Excess Specific Heat Consmption De to ~" :--.."" :--..' Part_ Loading IIIII II II I Manfactrer's Granteed SHC I Ta = 31 "c Ta =43 "c, Excess pecific Heat Consm1 tion De to Engine Degradation 15 I I I Genera~or r--.. Otpt M W " ~~fffr Fig. 14: Waste Energy De to Part-Loading and Engine Degradation, 137

22 Energy Stdy of a Gas-Fired Trbo-Generator operation dring peak load conditions in smmer time. The system spinning reserve of 12 MW minimm is also assigned to Ras Ab-Fontas power station. This spinning reserve may well exceed 18 MW for a good portion of the year de to sharp load variations. For example, there is an indstrial consmer who has a 6 MW frnace which is trned on and off twelve times a day!. To maintain he minimm spinning reserve, two trbo-generator nits need to be started p and sht down every two hors; this is not acceptable de to excessive maintenance cost. It is worth mentioning that among the 622 MW, which is the installed capacity of Ras Ab-Fontas station, there are 3 MW allocated for black start of the electrical power system and are not contribting to the load capability of the plant. With these factors in mind, an annal plant factor of.4 seems to be qite reasonable. Conseqently, trbo-generator nits are working at almost 5% load for most of their operating hors. For the prpose of this stdy, it may be interesting to see how mch excess heat is needed per nit power generated de to part-loading. Figre (14) shows excess SHC de to part loading. Figre (15) presents, in a simple way, the economic side of the problem. Based on the government-highly-sbsidized fel prices (.8 QR per 1 St. C. ft.), simple calclations reslt in a yearly excess fel for generating electricity, de to both part-loading and engine degradation of nit 2 alone, of the vale of 1.3 million QR. In the era when most natral gas was to be flared, the previos conclsion may seem to be of secondary importance. Bt nowadays, with most of natral gas prodced is being tilized (1), and frthermore the prospects of exporting it are serioslynsidered, we shold not ignore sch an amont of excess fel expended in the process of generating power, even thogh it might be sed either totally or partially, in water desalination, especially when international gas prices are taken into accont. The performance of the waste heat boiler-desalination nits and the extent to which we can sccessflly tilize additional heat associated with excess specific fel consmption are thoght to be an important area for ftre stdy. It shold be pointed ot however, that the present stdy is mainly concerned with gas trbine-generator nit alone. 1. CONCLUSION A discssion of energy consmption of 44 MW gas-fired trbo-generator nit led to 138

23 M.R.S. Okelah '..c 3 12 :1:: :: ' d t; 8- LJ 16 r-----r ~----~ Additional Fel Cost (Per MW.hr) De to Part-Loading 1 Additional Fel Cost (Per MW.hrl De to Q) ;::) IL VI VI Q) X w Or-----~~--~ _J------~--~1~. j Excess Sp cific Fel Consmption De to Engine Degradation..._ Excess Specific Fel. Consmption '-, De to Part-Loading Generator Otpt MW 5 45 c: E ' ~..c g3 LJ::L a;,.,' :::1 E _z:.::::lj IL li:;vl. V1 Fig. 15: Excess Fel Cost and SFC De to Part-Loading and Engine Degradation. 139

24 Energy Stdy of a Gas-Fired Trbo-Generator the conclsion that excessive specific fel consmption, de to performance degradation and part load operation of the nit, costs some 1.3 million Qatari Riyals annally. A rise of ambient temperatre slightly increases specific heat consmption; it redces however, power otpt sbstantially. The method of analysis is explained and relevant reslts validated by comparisonwith selected measred variables. ACKNOWLEDGEMENTS The athor wold like to thank Mr. M.Y. Al-Ali, Director of Electricity and Water Department, State of Qatar, for his contined spport of this research project. Thanks are also de to the staff of Ras Ab-Fontas Power and Water Station, especially Mr. Fahd Al-Mohannady, Depty Sperintendent of the station, and the staff of the maintenance department for their valable cooperation which made this work feasible. REFERENCES 1. PoweU Robin LlewUyn: "Ras Ab Fontas: Qatar's Sorce of Power and Water", Middle East Electricity, Sept. 1984, pages "Gas Trbine- Orders", Kraftwerk Union AG Pblications, Order No. A96- L175-X-X-76, Jly 1984, "Gas Trbines V93 - General Design Featres". Kraftwerk Union AG Pblications, , TGK. 4. "Indirect Determination of Mass Flow and Trbine Inlet Temperatre with Error Evalation for Single-shaft Trbines", Kraftwerk Union AG Technical Report: TG - Bericht Okelah, M.R.S.: "A Model for Field Performance Evalation of a 5 MW Indstrial Gas Trbine", Paper presented at the lasted International Conference on Modelling, Identification and Control, MIC '85, Grindelwald, Switzerland, Feb , "Smmary of the Annal Climatological Report ", Pblications of the Ministry of Commnication & Transport, State of Qatar,

25 M.R.S. Okelah 7. "Gas Trbine Description- Technical Data", Kraftwerk Union: 3.1-1/1, Code: Ras Ab Fontas I and II, T-No. 773, Date "Electricity & Water Dept. Statistical Report- Electricity -1984", Pblications of the Ministry of Electricity & Water, State of Qatar, Agrawal, R.K., Madsaac, B.D. and Saravanamttoo, H.I.H.: "An Analysis Procedre for the Validation of On-Site Performance Measrements of Gas Trbines", Transactions of the ASME, Jornal of Engineering for Power, Jly 1979, Vol "Annal Statistical Abstract, 5th Isse, Jly 1985", Pblications of the Central Statistical Organization, State of Qatar, "Gas Trbine Power Plant at Ras Ab Fontas", Kraftwerk Union AG Pblications, , March 1978, Order No. KWU