How To Evaluate Power Station Performance

Transcription

1 Proceeings of the Worl Congress on Engineering an Computer Science 20 Vol II, October 9-2, 20, San Francisco, USA Performance Evaluation of Egbin Thermal Power Station, Nigeria I. Emovon, B. Kareem, an M.K. Aeyeri Abstract-The main objective of this Paper was to evaluate the outage cost ue to system owntime (Turbine failure) of Egbin Thermal power station from the year 999 to The result of the analysis carrie out reveale that for the whole ten years uner review that there was a power generation loss of 46 percent of the capacity putting the performance of the power station at 54 percent. Further investigation which is the aim of the paper reveale that the 46 percent of prouction loss resulte to revenue loss to the tune of $24,86,569,250. However a simple performance inicator was evelope to evaluate the outage cost for the station which can also be applicable to other power station in Nigeria an beyon. Inex Term- generation reuction, outage cost, generate capacity, installe capacity, I. INTRODUCTION The history of electricity generation can be ate to 896, when the public works Department (PWD) ha 2 number of 30 KW generating plants powere by 2 number Davey- paxman locomotive type boilers ouble acting engines. The 60KW power generate by these 2 number of 30KW generators at 000V was istribute along Marina, Lagos by using ten overhea circuits of swg soli copper wires carrie on porcelain insulators supporte by iron poles. Interestingly the frequency of the generators as at that time was 80 cycles per secon against what we have toay as 50 cycles per secon, Manafa [] as cite by Usifo et al. [2] With the growth in inustrialization an population, there has been an increasing eman for electrical energy in Nigeria. Power generation in Nigeria is mainly from three hyro-electric power stations, steam an gas thermal stations. Most of these facilities are being manage by PHCN, a government owne utility company that coorinates all activities of the power sector be it prouction, transmission, istribution, or marketing an sales [3]. Since inception of PHCN, the authority expans annually in orer to meet the ever-increasing eman. Unfortunately, the majority of Nigerians have no access to electricity an the supply to those provie is not regular [4]. Manuscript receive March 24, 200. This work was supporte by the Feeral University of Petroleum Resources, Effurun, Nigeria, uner Grant FUPRE I. Emovon is with the Feeral University of Petroleum Resources, P.M.B.22, Effurun, Nigeria (phone: , ikuoy2k@yahoo.com) B. Kareem is with The Feeral University of Technology, P.M.B. 704, Akure, Nigeria ( karbil2002@yahoo.com) M.K. Aeyeri is with The Feeral University of Technology, P.M.B. 704, Akure, Nigeria ( saemike2003@yahoo.com) As at December, 2009 the number of Power stations in Nigeria was over 6, with installe capacity of 8,876 only 3,653 available. Thus 4% of the installe capacities were available [5]. The Nigerian power sector just like the ownstream sector of the oil Inustry has suffere ingloriously from poor maintenance problem [6]. The power stations coul not follow their maintenance an as such, most of the plant units in the Stations always pack up. The Country is wonerful in planning but implementation is zero. It is the government that approves fun for project because the Inustry is not fully eregulate. When fun is neee to overhaul a power station the Managers run back to government an if they o not provie funs, the units will be abanon. Things o not work this way. That is the may reason we avocate for complete eregulation in our earlier paper title power generation in Nigeria: Problem an solution [5]. One of the Power station that is worst hit is the Egbin Thermal Power Station an it is the focus of this paper. However the main objective of this paper is to evaluate the outage cost ue to system owntime(turbine failure) of Egbin Thermal Power Station from the year 999 to EGBIN THERMAL POWER STATION Historical Backgroun The Feeral Government in 982 uner Presient Shehu Shagari mae a lan mark ecision to site a Thermal power station near Lagos in orer to solve the perennial problem of inaequate power supply in the nation. At that time, Lagos metropolis power eman ha grown to about 40% of the total energy generate. Egbin is a steam power plant with 6 installe units each having a capacity of 220Mw totaling installe capacity of 320 Mw. Accoring to [3], they are ual fire (gas an heavy oil) with moern control, single reheat; six stages regenerative fee heating. The first unit of the power station known as ST- 3 was complete an commissione on th May 985. The remaining five units were commissione one after the other within intervals of 6 months. Therefore between May 985 an November 987, the entire six units were hane over for commercial operation in the orer: 3, 2,,4,5, & 6, by Marubeni/Hitachi of Japan. Since commissioning, the station has remaine the single largest power station in the country contributing between 30% - 40% of the gri require. It is also the biggest power station in West Africa sub-region [7] The station was commissione on oil firing. However Gas firing starte in October 988. The power station has been generating power far below installe capacity ue to maintenance problems. These problems have affecte the availability an reliability of the power plant. However the maintenance management functions inclue both reactive an preventive. The PM type

2 Proceeings of the Worl Congress on Engineering an Computer Science 20 Vol II, October 9-2, 20, San Francisco, USA in place is time base, which is not effectively carrie out, not to talk of practicing the state of art preictive maintenance. The preventive maintenance proceure an intervals are not well efine. Poor plant history recors make it ifficult to retrieve plant history an reports of plant/equipment, especially for ol plants. This has resulte to the power station generating power far below installe capacity. Hence the Power generation reuction was evaluate in orer to etermine the outage cost ue to system owntime. Major Plant Component There are four major components of the steam power plant[7] namely: Boiler: The emineralize water is sent to the boiler rum before lighting off the boiler an is later introuce as make up water at the hot well to augment for losses. The boiler has 9 sets of natural gas fuel burners, the natural gas is supplie to Egbin by NGC a subsiiary of NNPC. Two burners are lighte off to pressurize steam. The boiler has a capacity of generating steam at 705 t/h. The Boiler is ual firing. It uses either natural gas or High/Low Pour Fuel Oil( HPFO/LPFO ). Turbine: The turbine is a Tanem Compoun Double Flow Reheat conensing tube type with 9 stages of expansion. The high pressure stage is an impulse- velocity compoun type, while the LP stage is the reaction type. As the steam flows through the turbine blaes, perpenicular force is inuce on the rotor blae causing the rotor to revolve at high spee. The superheate steam at a pressure of 2500kpa an a temperature of 538 O C turns the turbine at a spee of 3000rpm.Turbine rating is 220Mw. Conenser: The exhaust steam at a pressure of 8.5kpa from the LP turbine is conense to water at the conenser.the conenser is a heat exchanger which is kept uner vacuum through the steam jet air ejector.circulating water from the lagoon goes through the conenser tubes while exhaust steam falls on the surface of the tubes which conenses to water an is recycle to the Boiler rum as fee water. Generator: The generator is irectly couple to the rotor of the turbine so they both turn at 3000rpm. It generates a 3- phase AC power of 220 MW at full capacity. Its winings are excite with a DC 440v. The winings are coole with hyrogen gas at a pressure of 20 kpa.the generator current is 8.87A, with output voltage of 6kv, before being steppe up to 330kv by the generator transformer for onwar transmission to loa centres. The unit transformer steps own the voltage from 6kv to 6.6kv for Unit auxiliaries use. II. METHODOLOGY An extensive literature survey was carrie. This was achieve by browsing on the internet, subscribing for journals, conference papers an contacting experts for information on power generation an existing ways of evaluating performance. One month visit to Egbin Thermal Power station was embarke upon. During the perio all relevant Data were obtaine from Plant recors. Data obtaine inclues; installe power generation capacity, generate capacity in MW an MWh among others as shown in Tables I,II,III,IV,V,VI,VII,VIII,IX an X. Finally a simple Performance inicator were evelope to evaluate the outage cost for the Power Station. Performance Inicator P T = i n P Ai P T = Total power outage cost ue to system owntime for n number of years, P A = Annual power outage cost for M number of Turbine, But P A = P R X P F X C U ( 2) P R = J M P r Pr = P IC P GC (4) P R = annual power reuction for M number of turbine P r = annual power generation reuction for iniviual P IC = annual installe capacity in MWh for iniviual P GC = annual generate capacity in MWh for iniviual turbine P F = G c / I C (5) P F = annual power factor for M number of G C = generate capacity in MW for iniviual I C = capacity in MW for iniviual C U = unit cost of power For the purpose of the research, we assume unit cost of power to be US$ 0.70 KWh () (3)

3 Proceeings of the Worl Congress on Engineering an Computer Science 20 Vol II, October 9-2, 20, San Francisco, USA Table I: Year 999 Power generation Parameters Unit ST- 220,927, ,672,562 ST-2 220,927, ,685,478 ST-3 220,927, ,359,482 ST-4 220,927, ST-5 220,927,200 93,205,435 Total,320,563, , Table II: Year 2000 Power Generation Parameters Unit ST- 220,927, ,563,564 ST-2 220,927, ,356,900 ST-3 220,927, ,294 ST-4 220,927, ST-5 220,927, ,732,890 Total,320,563, ,09,648 Table III: Year 200 Power Generation Parameters Unit ST- 220,927, ,652,222 ST-2 220,927, ,753,524 ST-3 220,927, ,72,268 ST-4 220,927, ,204,487 ST-5 220,927, ,65,589 Total,320,563, ,974,090 Table IV: Year 2002 Power Generation Parameters Unit ST- 220,927, ,324,090 ST-2 220,927, ,520,460 ST-3 220,927, ,370,025 ST-4 220,927, ,325 ST-5 220,927, ,38,533 ST-6 220,927, ,07 Total,320,563,200, ,87,504 Table V: Year 2003 Power Generation Parameters Unit ST- 220,927, ,43,54 ST-2 220,927, ,59,000 ST-3 220,927, ,4,902 ST-4 220,927, ,35,279 ST-5 220,927,200 43,97,206 ST-6 220,927,200 34,2,900 Total,320,563, ,889,828 Table VI: Year 2004 Power Generation Parameters Unit ST- 220,927, ,339,773 ST-2 220,927, ,30,468 ST-3 220,927, ,42,83 ST-4 220,927, ,538,443 ST-5 220,927,200 57,202,82 ST-6 220,927,200 5,265,3 Total,320,563,200, ,068,360 Table VII: Year 2005 Power Generation Parameters Unit ST- 220,927, ,364,226 ST-2 220,927, ,529,428 ST-3 220,927, ,458,950 ST-4 220,927, ,435,890 ST-5 220,927,200 80,38,40 ST-6 220,927,200 65,422,00 Total,320,563,200, ,59,905 Table VIII: Year 2006 Power Generation Parameters Unit ST- 220,927, ,052,77 ST-2 220,927, ,652 ST-3 220,927, ,879 ST-4 220,927, ,333 ST-5 220,927, ,33 ST-6 220,927, ,836 Total,320,563, ,004,00

4 Proceeings of the Worl Congress on Engineering an Computer Science 20 Vol II, October 9-2, 20, San Francisco, USA Table IX: Year 2007 Power Generation Parameters Unit ( MWH) ST- 220,927, ,460 ST-2 220,927, ,04,622 ST-3 220,927, ,649 ST-4 220,927, ,338 ST-5 220,927, ,40 Total,320,563, ,875,479 Table X: Year 2008 Power Generation Parameters Unit ST- 220,927, ,052,64 ST-2 220,927, ,88 ST-3 220,927, ,649 ST-4 220,927, ,267 ST-5 220,927,200 55,28,88 Total,320,563, ,386,456 III. DATA COMPUTATION To calculate the total power outage cost (P T ) ue to system own time for the ten years uner review, we applie () to (5). Firstly we calculate annual power outage cost (P A ) for the year 999 using ata in Table I. However to obtaine P A the following three parameters P F, C U an P R are neee. Using (5) to calculate power factor (P F ) we have; P F = 989.9/,320 = The power factors for the year 999 to 2008 is shown in Table XII Also using (3) an (4) we calculate annual power reuction for the six turbine as emonstrate in Table XI below; Table XI: Annual power reuction calculation Turbine capacity(p IC) capacity (P GC ) Power generation reuction (Pr = P IC P GC ) ST-,927,200,672, ,638 ST-2,927,200,685,478 24,722 ST-3,927,200,359, ,78 ST-4,927, ,927,200 ST-5,927,200,205,435 72,765 ST-6,927, ,927,200 P R = 6 p r 5,640,243 We followe the same proceure to obtain P A (2000), P A (200) P A (2008). Finally we applie (5) to obtaine total power outage cost for the ten years to be $24,86,569,250 Table XII: Annual capacity factor Year Factor capacity capacity 999, , , ,320, , ,320, ,320, , IV. RESULT AND DISSCUSSION For the whole perio of ten years uner review, we critically look at the generate capacity against the installe generation capacity, results as shown in Table XIII an fig. below. Table XIII: Power generation reuction Year Generation reuction % reuction % Available 999 5,640, ,543, ,589, ,69, ,673, ,494, ,97, ,559, ,687, ,76, Total 53,027, % Reuction / % Available Year % Reuction % Available Fig. : Power generation reuction 2009 C U is assume to be US$ 0.70 KWh Therefore substituting values of P F, P R an C U into (2) we have; P A (999) = 5,640,243 X X 0.7 X 000 = $2,96,27,575 The result reveale that there was power generation reuction between the range of 26 to 62 percent. Base on the installe capacity the station was expecte to generate 5,632,000MWh of electricity from the year 999 to 2008.

5 Proceeings of the Worl Congress on Engineering an Computer Science 20 Vol II, October 9-2, 20, San Francisco, USA However there was generation reuction of 53,027,763MWh amounting to 46 percent. This put the performance of the power station for the perio uner review at 54 percent. Next we calculate the loss of revenue in ollars base on the power generation reuction of 46 percent. The result is as shown in Table XIV an fig. 2 below Table XIV: Outage cost ue to system owntime Year Power outage cost in ollars(p A ) 999 3,09,238, ,82,48, ,876,745, ,55,687, ,3,298, ,888,6, ,690,963, ,777,86, ,776,804, ,773,093,882 Total 24,334,680,000 Outage cost Year Fig.2: Outage cost in ollars ue to system owntime 2008 The result reveale that that from the year 999 to 2008 the total outage cost ue to power generation reuction of 46 percent is to the tune of $24,86,569,250. From our finings the losses in generation is as a result of so many problems face by the Power Station. Some of these problems inclues; late release of capital subventions, inaequate working capital, ageing plant an machinery an poor maintenance programme V. CONCLUSION From available recors of Egbin Thermal power station, there appear to be no proper preventive maintenance programme in place. This an many other factors has resulte to the station generating power far below installe capacity. The analysis carrie out reveale that the station was expecte to generate a total of 5,632,000MWh of electricity from the year 999 to However there was power reuction of 53,027763MWh amounting to 46 percent. Further investigation which is the main objective of this paper reveale that the 46 percent loss of prouction resulte to revenue loss of $24,86,569,250. This is no mean amount. This shoul be an eye opener to the Feeral Government of Nigeria on the nee to invest in the power sector in orer to get goo return on investment. ACKNOWLEDGMENT Emovon, I. thanks the managements of the Feeral University of Petroleum Resources, Effurun, Nigeria for proviing an enabling environment for carrying out this stuy. REFERENCES [] M. N. A. Manafa, Electricity evelopment in Nigeria ( ), st e. Lagos: Raheem publishers, 978, pp.4-70 [2] O. Usifo, S. Omoruyi, F. Igbinovia, an P. Otasowie, Electrical power sector energy Reform prospects in Nigeria, Nigerian Journal of Engineering management, vol.8, no.3, pp. -4, [3] Aelaja A.O., Ogunmola, O.Y. an William: E.O.(2007) ao_aelajayahoo.com [4] O. I. Okoro, an T. C. Maueme, Solar Energy Investments in a Developing Economy, Renewable Energy, vol. 29, pp , [5] I. Emovon, M.K. Aeyeri, an B. Kareem, Power generation in Nigeria; Problems an solution, presente at the 20 Int. Conf. Nigerian Association for Energy Economics, Abuja, Nigeria, [6] M. Ayankola, Revisiting the power sector an poor maintenance culture, 2th October, 2008 Punch Newspaper. [7] G. E. Omokohe, Egbin Electric Power Business unit, Nigeria, private communication, February 20