Experience Gained in Operation of the GTS Finnjet Gas Turbines and. Py^kkanen Improvements in Ship's Fuel Vice President, Development

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1 THE AMERICAN SOCIETY OF MECHANICAL ENGINEERS 345 E. 47 St., New York, N.Y GT-295 ^+ The Society shlt not be responsible for sttements or opinions dvnced in ppers or in G discussion t meetings of the Society or of its Divisions or Sections, or printed in its c) publictions. Discussion is printed only if the pper is published in n ASME Journl. ]L Relesed for generl publiction upon presenttion. Full credit should be given to ASME, the Technicl Division, nd the uthorts). Ppers re vilble from ASME for nine months fter the meeting. Printed in USA. Copyright 1982 by ASME Experience Gined in Opertion of the GTS Finnjet Gs Turbines nd. Py^kknen Improvements in Ship's Fuel Vice President, Development. Sunmki Economy Mnger - Finnjet Powerplnt Overhul This pper briefly describes the use of gs turbines of the GTS Finnjet, mtters y Finnlines Ltd., concerned with mintennce nd repir s result of four yers' experience (45,000 elsinki, Finlnd engine hours) in service, using light distillte fuel. The reserch nd modifictions required for chngeover to blended residul fuel oils in gs turbines re then reviewed, s well s the first experiences (4,000 engine hours) in using the blended fuel oils during the summer of Finlly we describe how the fuel economy ws further improved by instlling diesel-electric mchinery on the cr deck to be used for mnoeuvring nd low seson journeys. NOMENCLATURE 1 B First stge turbine blde BFO Blended fuel oil FF Fuel flow HP High pressure LP Low pressure Ni Low pressure rotor speed (r.p.m.) N2 High pressure rotor speed (r.p.m.) NGV Nozzle guide vne SEM Scnning electro microscope TET Totl engine time TT7 Exhust gs temperture ( C) UTI United Technologies Interntionl 1 V First stge turbine vne TBR Time between removls INTRODUCTION The gts Finnjet is 30.5 knot gs turbine powered cr nd pssenger ferry, ordered from Wrtsil Helsinki shipyrd t the end of 1973 by Enso-Gutzeit Oy, prent compny of Oy Finnlines Ltd. The Finnjet hs been designed for the Finnlines Bltic Route between Helsinki nd Trventunde nd entered service in My Severl different types of vessel nd propulsion mchinery were exmined for this 600 nuticl mile route during the design phse between 1969 nd The most dvntgeous lterntive ws seen to be fst, high cpcity vessel which could be used very efficiently (deprture every dy t the sme time, mx. 1,560 pssengers nd 400 crs on bord, 22 hours journey nd two hours turnround). As min propulsion units ero-derived gs turbines (Prtt & Whitney type FT4C-1D) were chosen, minly becuse of their smll size, lightness nd ese of shore bsed mintennce. Diesel mchinery ws not considered possible becuse the dditionl weight would consume n dditionl 6,600 kw. lrforeover, tht kind of instlltion would hve been imprcticble in cr ferry with continuous cr deck. GAS TURBINE MAINTENANCE There re no stted intervls for overhul of the gs turbines. Repirs re crried out s required by engine condition. The gs genertor is constructed from esily exchngeble modules so tht repir times re the shortest possible, nd the best utilistion is ttined. Contributed by the Gs Turbine Division of the ASME.

2 The ship normlly hs four engines vilble for use, two instlled nd two spres. On ccount of the chngeover to hevier fuel oil we hd procured fifth engine for opertions in summer Chnging of engines t se cn be crried out if necessry in bout two hours, during which time the vessel's speed is decresed by bout six knots, nd the effect on the ship's schedule is bout 20 minutes in deep wter. However, normlly the engine chnges re crried out in shllow wter ner TrvemUnde, nd the effect on ship's schedule is only few minutes. If the engine inspection, mintennce, or fult repir lsts more thn two hours, the engine is exchnged nd the removed engine left in Helsinki for renovtion. WORKSHOP The engine is tken into the Finnlines workshop, where it is dismntled sufficiently to remove the module or prt to be repired. After clening, inspection nd repir the engine is ressembled using exchnge modules nd spre prts s required. A complete module exchnge opertion tkes bout 70 mn hours. Those removed prts nd modules which we do not repir ourselves re sent to subcontrctors to be refurbished. For exmple, high-pressure compressors nd high- nd low-pressure turbine modules re repired t Helsinki in the Finnir engine overhul shop. EXPERIENCE GAINED USING LIGHT DISTILLATE FUEL OIL IN THE PERIOD Tble 1 'RUNNING HOURS AND START UPS Strbord: 21,211 hrs, strts: 1711 Port : 23,840 hrs, strts: 1611 'Gs turbine Totl time Free turbine Totl time Seril No. Seril No , ,012 SB , ,876 BB , ,639 BB , ,068 SB TOTAL: 45,051 TOTAL: 45,051 An economicl TBR of 3,000 hours for the gs turbines ws estblished due to wer in the highpressure compressor 9th stge midspn shrouds nd lowpressure turbine 3rd stge blde notches. As result of this wer the bldes become loose, which leds to higher wer rtes. If not replced for refurbishment, dditionl opertion would increse the eventul scrp rte. The engine mnufcturer, United Technologies, is presently engged in progrm in connection with these problems, nd modified 9th nd 3rd stge bldes re currently in service evlution with Finnlines. After four yers in service the performnce of the gs turbines ws still quite stisfctory, s cn be verified from figure 1. TT7 hd incresed 1.2 per cent, corresponding bout 7 C t bse lod. L Nl N2-1 E -2 0 cc TT FF TET since new (x 1000 hrs) Fig. 1 Deteriortion of performnce (eng ) during 4 yers using distillte fuel. The free turbines hve stood up to use s expected. The port unit hs been exchnged once becuse of excessive wer in the No. 7 bering outer rce. During the four yers there hd been 48 engine chnges nd four free turbine chnges. There were in ll 18 scheduled repir chnges nd 12 unscheduled repirs; chnges s result of hevy fuel oil testing numbered 6 nd convenience chnges 12. (See tble 2.) OTHER SHIP'S MACHINERY Reduction gerbox: In 1978 lrge crck ws found in the bull wheel between the hub nd the tooth ring t the weld, nd the bull wheel hd to be replced. Further, we found tooth crck in the port side 2nd stge pinion nd two crcks in the sme stge on the strbord side. Rudders: As result of fulty design the rudders eroded rpidly from the beginning. The cuse ws tht the shft brcket ws set t wrong ngle which led to rudder cvities. Therefter only smll nnul repirs were found necessry. Automtic control: No prticulr problems were found nd the equipment worked rther well, only norml service being required. FnP1 control The Hmilton Stndrd electronic fuel control unit developed few smll fults ech yer which were repired on bord. During the whole period fctory service ws only required on one occsion. FUEL OILS In the first phse light fuel oil ws used in gs turbines, the uxiliry diesels nd the stem boilers. It ws decided in 1979 tht from the summer of 1981 wshed blended fuel oil would be used in the gs tur- 2

3 Tble 2 UNSCHEDULED REMOVALS AS A RESULT OF FAULTS IN GAS TURBINES Reson for removl Fult Prt totl time 1. Excessive spred of exhust gs Microbic growth in fuel tnk nd clogging 545 temperture of filters in fuel nozzles 2. Bldes dmged by loose prt from Piece broke off inlet cse guide vne nd 2,352 inlet cse ws drwn into engine 3. Crcks in high pressure compressor Blde mnufcturing fult 530 9th stge midspn shrouds 4. As in 3 bove As in 3 bove Vibrtion in high pressure compressor No. 2 thrust bering filure 2, As in 5 bove No. 2 thrust bering filure in sme 858 engine 7. As in 5 nd 6 bove Ftigue filure in 11th stge blde root 3, Metllic chips in oil filter Bering filure in oil scvenge pump 14, Externl oil lek Ftigue filure in oil pipe 7, Excessive oil consumption Dmged oil pipe, No. 6 bering 9, Excessive oil lek Dmged crbon sel of 4 1/2 bering. NA Sme engine s bove 12. Wek noise in low pressure compressor Counterweight edge broke loose 15,660 bines, nd residul fuel oil in the boilers nd uxiliry diesels from the end of The blended fuel oil used is mixture of light distillte nd of residul fuel with viscosity of 230 cst/50 C. The lkline metl slts will be removed from the residul fuel component t the Neste Oy Nntli refinery, using n electrosttic fuel wshing system so tht sodium nd potssium content in the fuel is less then 0.6 mg/kg. The viscosity of the finl blended fuel oil is below 50 cst/50 C. The wshed blended fuel oil is used in the gs turbines t cruising speed. Consumption is bout 300 tons per dy. Light fuel oil is used in gs turbines only for strting, mnoeuvring, nd stopping. FUEL SYSTEM At bse lod the temperture of the blended fuel oil is 100 C, the viscosity 8 ct, nd pressure 48 br in the fuel mnifold inlet (Fig. 2). Two boilers supply stem for fuel heting. Finnjet tkes in hevy blended fuel oil t the Helsinki terminl, where there is bunker sttion cornprising 3 10,000 m3 hevy oil underground tnk nd 1,000 m light oil tnk. Fuel bunkering 9kes one hour 20 minutes, nd in summertime bout 650 m is tken on bord every other dy. HEAVY FUEL OIL RESEARCH Reserch into the use of hevy oil in Finnjet gs turbines ws begun bout five yers go. We exmined severl different pplictions nd systems but did not find one which we could hve pplied directly. We sp Storge 0 ettlin O D O tnk, nk y, I_! rte- 4_ F Mg-dditive treting Gs tur- ' system bine fuel. nozzles : Fuel '" control Light unit fuel oil ig Schemtic of fuel system on bord for gs turbines 1. Storge tnk 2 x 700 m Sttic mixer 2. Settling tnk 2 x 150 m Duplex fuel filter 3. Plte het exchnger (10 jn nom.) 4. Seprtor High pressure fuel 5. Dy tnk 2 x 60 m pump 6. Plte het exchnger 15. High pressure fuel 7. Automtic bck flushing filter (40 3n nom.) fuel filter (10 Jn nom.) 16. Fuel modulting vlve 8. 3-wy vlve 17. Pressuring nd dump 9. Light fuel system vlve 10. Mg-dditive 18. Fuel nozzles 48 totl 11. Additive treting system 19. Electronic fuel control unit ^ 3

4 Tble 3 GTS FINNJET FUEL SPECIFICATIONS ORIGINAL LIGHT DISTILLATE USED FOR GAS TURBINES START/STOP WASHED BLENDED FUEL OIL USED FOR GAS TURBINES AT CRUISING SPEEDS RESIDUAL FUEL OIL WILL BE USED FOR MAIN AND AUXILIARY DIESELS AND BOILERS Specifiction Test method Specifiction Test method Specifiction Test method Sulphur, % wt <0.80 DIN <3.0 DIN <.3.4 DIN Distilltion, C ASTM D % % 282 Flsh point, P - M, C > 56 ASTM D 93 > 60 ASTM D 93 > 56 ASTM D 93 Grvity, kg/m ASTM D 1298 <0.93 ASTM D 1298 Viscosity, mm 2 /s 20 C ASTM D C < 50 ASTM D 445 < 233 ASTM D 445 Cloud point, C < 2 ASTM D 2500 Pour point, C S 0 ASTM 97 Crbon residue, Rmsbottom, on 10 % dist. residue, % 0.25 ASTM D 524 Conrdson, F <6.0 ASTM D 189 Net het comb., MJ/kg 41.9 ASTM D 240 Sediment, mg/l C 10 ASTM 2276 ASTM D 1796 <0.2 ASTM D 473 Free wter, mg/1 < 60 ASTM D vol. < 1.0 ASTM D 95 Wter + Sediment, F vol. <0.2 Ash, % wt < 0.2 EN 7 mg/kg 15 ASTM 482 <400 EN 7 Metls, mg/kg V IP 286/72 < 70 N + K ASTM, SIP 531 <0.6 ASTM D 2788 C <5.0 Pb 0.5 IP 224 (modified) cified the fuel requirements in collbortion with United Technologies, the engine mnufcturer, nd the fuel supplier (Neste Oy) on the bsis of results obtined from the mnufcturers' hevy fuel oil test engine nd lso Setrin continer vessel opertions using blended fuel oil in similr gs turbines. Subsequently problems connected with combustion, hot corrosion nd build-up of sh deposits hd to be solved. In our reserch, we enlisted the id of number of experts nd lbortory estblishments, nd dditionlly crried out bout 50 test runs on bord over two yer period. COMBUSTION This kind of gs turbine ws not designed specificlly for use with hevy fuel oil, there ws risk tht the combustion chmbers would be too short nd the flmes would rech the turbine. By improving the fuel tomistion, combustion time nd flme length could be shortened nd risks reduced. In the Setrin gs turbines, stisfctory results were obtined by dding wter to the fuel, which, with the id of homogenizer, emulsifies with the wter t high pressure (200 br). With wter thoroughly mixed in the oil droplets when het is dded in the combustion chmber, so-clled micro-explosion tkes plce, s result of which the fuel droplet size diminishes gretly nd the combustion time shortens. In our cse the procurement of homogenizer nd construction of working system might hve proved reltively expensive, s there ws no proof of it being bsolutely necessry. Also, there ws some evidence of the wter recting dversely with some of the Mgdditives, cusing deteriortion of the dditive compound nd subsequent fuel nozzle clogging. Using different pproch to improving tomistion, new design of nozzles ws used in the mnufcturers' hevy fuel test gs turbine; tomistion being improved by the use of high pressure ir (200 br). These ir-boost nozzles hve been under test thus fr for bout 1,000 hours, nd ccording to the mnufcturer hve been successful. Since the nozzles nd sso- 4

5 cited systems re in the prototype stge, delivery would hve been too long for us to consider. The fuel nozzles currently in generl use hve never been used extensively with hevy fuel oil but in the mkers'opinion combustion nd engine opertion should be stisfctory providing tht close control of the fuel nd the necessry on bord systems ws mintined. Bsed on this, we decided to experiment with the originl fuel nozzles. If the result hd not proved stisfctory, we would hve hd to dopt either the homogenizer or ir boost nozzle system. The experiment succeeded nd the experience gined thus fr indictes tht the originl equipment combustion system cn hndle the blended fuel oil. HOT CORROSION In order to void hot corrosion, the melting point of turbine mterils nd sh deposits must be higher thn the gs temperture (Fig. 3). 4-) 1000 G, 800 F verge gs tem. 900 verge metl temp 700 cooled cooled cooled 1V 1B 2V 2B 3V 3B Turbine irfoil Fig. 3 FT4C-1D turbine temperture profile t bse lod by UTI When using residul oils, hot corrosion will be cused by vndium in the fuel (in ddition to sodium nd potssium slts). Bsed on other experiments it is known tht vndium corrosion cn be completely prevented by using mgnesium dditive. V MgO Mg3 (VO4)2 The sh melting point of the resulting compound is then so elevted tht there is no corrosion risk. The required mount of mgnesium depends upon the vndium content in the fuel. In the idel sitution complete chemicl rection is chieved when the weight rtio of Mg/V is From experimentl resuits it is known tht there is no corrosion of vndium when Mg/V rtio is greter thn 3.0. (Ref. Design nd Technology of 80's, Generl Electric Europen Gs Turbine Seminr 1980.) At this rtio, however, the build-up of deposits on the turbine prts would be so rpid tht it would seriously impir the efficiency of the gs turbine. In lowering the rtio Mg/V to 2.0 the build-up rte is cceptble. The composition of the deposits is similr to tht occurring when the rtio Mg/V ws 3.0. In both cses the mount of corrosive compounds present (wter soluble vndtes) ws insignificnt. During the summer we ccidentlly used blended fuel oil (V = 65 p.p.m.) for 94 hours t 1:1 Mg/V rtio. The mistke ws result of the oil supplier giving incorrect informtion s to the vndium content. In the nlyse of the deposits it ws confirmed tht the wter solubility t this rtio ws essentilly worse thn t 2:1 rtio. However, the quntity of corrosion cused by the wter soluble vndtes ws so smll tht visul inspection only showed some slight trces of dmge to the coting of turbine bldes nd vnes. This confirms tht using 2:1 Mg/V rtio provides sufficient sfety mrgin in terms of vndium corrosion. MAGNESIUM ADDITIVES The more generlly used mgnesium dditives re Mg-sulphte (wter soluble), Mg-sulphonte (oil soluble), nd Mg-oxide or Mg-hydroxide (in suspension). The end result is similr whichever form of Mg dditive is used in the fuel, but the nture of the existing fuel system imposes certin other requirements. For exmple, Mg-oxide cuses blocking of depth-type filters nd dditionlly leds to erosion of the fuel nozzles. We chose the oil-soluble Mg dditive (Kontol K I-16), becuse it is simple to use nd it should not hve cused difficulties in other prts of the fuel system. The use of this dditive, however, cused blockge of the fuel filters (Fig. 2, item 13) in less then 20 hours. After the dditive hd been clened by using 10 micron filtrtion, the fuel filter exchnge intervl ws incresed to bout 60 hours. Lbortory nlysis showed tht 60 F of the mteril cusing fuel filter problems ws mgnesium crbonte. According to the mnufcturer of the dditive the Mg-crbonre ws creted by the high temperture (128 C) of the stem heting coils in the dditive tnk on bord. The difficulties could be eliminted by using hot wter (60 C) insted of stem for dditive heting. GAS TURBINE MATERIALS AND COATINGS High hot corrosion resistnce of bse mterils nd cotings is one of the most importnt requirements in using residul oils. The mterils nd cotings minly in use re: Tble 4 BASE MATERIALS COATINGS 1st blde Inco IM 6250 (CoCrA1Y) 2nd blde Inco PWA 70/268 (Cr/CoCrA1Y) 3rd blde Inco PWA 73 (Al Si) 1st vne Mr-M-509 PWA 268 (CoCrA1Y) 2nd vne Mr-M-509 IM rd vne Inco PWA 268 SALT REMOVAL Sodium negtes the effectiveness of mgnesium tretment. V NCl --+ N VO 3 MgO According to the mnufcturers' reserch, sodium ccelertes hot corrosion in ccordnce with the grph in Fig. 4. 5

6 I N Time (hrs) Fig. 4 Burner rig vndium inhibition t C ccording to UTI Fig. 5 A x 5000 mgnifiction of deposit smple from 1st stge nozzle guide vne S ^ n United Technologies' recommendtions for the mximum slt content llowed in the combusion rection should be less thn 1.0 p.p.m. When the sodium content in the fuel is 0.6 p.p.m., only 0.05 p.p.m. is llowed in the suction ir. The three stge demisters instlled in Finnjet hve kept the ir slt content below this limit. The slt content of blended fuels is p.p.m. before wshing. The seprtion process for removing slt from the fuel should hve been techniclly cceptble for use on bord ship, but the slt content specifiction ws so stringent tht the cpcity of n on bord wshing system my not hve been sufficient to mintin the specifiction limit. In considering the investment nd opertionl risks the svings chieved were not sufficiently lrge, so tht we decided to crry out slt removl on shore. DEPOSITS The use of mgnesium dditives resulted in buildup of deposits on the turbine bldes nd vnes. This decreses turbine efficiency by bout 4 1 during one journey. In order to mintin the required power, fuel flow hd to be incresed ccordingly, resulting in the exhust gs temperture (TT7) pproching the mximum recommended vlue. For this reson the build-up of deposit lyers must be kept to minimum nd the efficiency restored to its former level by clening the turbine in port fter ech journey. The deposit is minly composed of mgnesium sulphte (wter soluble), the sinter point of which is so low tht it bonds to the blde nd vne surfces. In Fig. 5 there is x 5,000 mgnifiction of the 1st stge nozzle guide vne triling edge, the smple being tken close to the blde mteril. The sintering cn be verified from the necking between molecules. Elements Fig. 6 The intensity rtio of Mg nd S corresponds to molr rtio 1:1. This indictes tht the min prt of the deposit is MgSO 4. In Fig. 6 the sme smple is nlysed using n ISI Mini-SEM-PGT 1000 X-Ry nlyser. The vndium content in the smple is prticulrly smll lthough the vndium content in the fuel oil ws 43 p.p.m. On the leding edge nd concve surfce of the 1st stge turbine nozzle guide vne there is hrd deposit which when dry is very difficult to remove. On the rer surfce is soft, loose, slightly gresyfeeling lyer. The cooling holes in the vnes will remin open despite of deposit formtion. On the 1st stge turbine rotor blde leding edge nd front side is n even thicker, very hrd nd dense lyer. During running, prt of the deposit will brek free from the leding edge. The rer surfce hs similr soft thin lyer to tht of the nozzle guide vne. The deposition build-up on the 2nd nd 3rd stge turbine bldes nd vnes occurs in similr mnner but t much slower rte. 6

7 The following grphs (the best liner fit of experimentl points) show the min trend of the deposition rte with different fuels (Fig. 7). 5 0' ^ o ^ 'ti 2 1 ro 4 4 c Additive/vndium rtio Fig. 7 Increse of exhust gs temperture (TT7) using different kinds of fuels nd dditive/v rtios The cut-off curve shows how the silicon dditive ffected the deposition rte. The best result ws obtined when Si/V = 1.0 nd Mg/V = 3.5. In using silicon the deposit ws no longer wter soluble nd it ws very difficult to remove from the surfce of turbine prts. When vndium content in the fuel ws incresed from 43 p.p.m. to 70 p.p.m., the deposit formtion ws slightly slowed down. Deposition built-up rte is followed from the performnce monitoring grphs (Fig. 8). N c N2 0 C TT FF 0 TET since lst wter wsh (hrs)v Fig. 8 Deteriortion of engine performnce during one journey using blended fuel oil Illustrted is typicl run using residul blended fuel (V = 70 p.p.m.). The exhust gs temperture rises steeply t the beginning, then levels off to the end of the run. The N1 grph shows the lowpressure rotor nd N2 the high-pressure rotor decrese in rottionl speed. The fuel flow (FF) rises stedily nd is t the end of the run bout 6 litres/minute higher thn t the beginning. Following the wter wsh, the engine performnce is restored to Other problems cused by deposits Test runs (450 hours) were crried out during the winter using the GG4C-1 gs turbine. At the beginning of the summer when we begn to use the uprted GG4C-1D version turbines, two new problems rose: 1. Immedite turbine reccelertion fter lrge power reductions could not be chieved becuse of the dirty turbine. After n idle running period of 1-3 minutes, opertion returned to norml for the time being. There is criticl re just bove the idle running speed where the engine will stll if it is ccelerted too strongly. The electricl fuel control unit, which hs built-in ccelertion schedule to prevent stlling, tkes into ccount rotor speed (N2), exhust gs temperture (TT7), nd outside ir temperture (OAT). The reltionship of these prmeters chnges in dirty engine, nd the ccelertion sche - dule does not llow engine ccelertion without the idle running puse to llow cooling. In order to eliminte this dely the ccelertion schedule ws redjusted closer to the criticl stlling re. This procedure improved the sitution but the results were not entirely stisfctory nd creted further problem in tht the engine begun to stll t the ccelertion stge (s we hd fered). This problem cn be solved by ccelerting the engine slowly in the criticl re. In prctice this is crried out by ccelerting from idle speed using the gs turbine speed control until the criticl re hs been pssed through, the propeller speed control then tking over, this being the norml mnoeuvring mode. 2. The compressors of the GG4C-lD engines stlled strongly lso during decelertion. The stlling ws eliminted by redjusting the bleed vlves which re sited between the high nd low stge compressors. WATER WASH Deposits re utomticlly wshed wy in ech port. Wshing time is 20 minutes per engine. During the wshing procedure the free turbine is rotted by gered motor, since without rottion only prt of the rotor bldes would be clened, thus cusing excessive vibrtion t strt up. H.P. wter wsh 2 x 140 1/min 120 t 250 I r 1/mini 1/min Wter drin L.P. wter wsh 650 1/min input 270 1/min Fig. 9 Loction of high nd low pressure wter wsh nozzles nd drin pipes 7

8 1. Wshing in port is begun by cooling down the MODIFICATIONS AND INVESTMENTS engine using the strter motor to rotte the engine, 2. During the cooling phse, two high pressure 1. At the Finnjet bunker sttion new recirculting fuel heting system nd incresed pumping c- wter wsh nozzles re instlled. 3. A high pressure piston pump nd nozzles re pcity hve been constructed. used to jet flt fn-shped spry between two nozzle 2. On bord Finnjet new tnk rrngements hve guide vnes nd into the 1st stge rotor bldes, The been mde, more efficient het exchngers nd fuel wter pressure is 375 br, temperture 60 C, nd flow filters procured, nd Mg-dditive system nd wter rte 140 litres/minute per nozzle. wsh system instlled. 4. Simultneously the low compressor inlet is 3. Two bosses hve been welded in through the spryed with hot wter t pressure of 5 br nd gs turbine combustion outer cse to crry the high rte of 120 litres/minute nd the combustion chmber pressure nozzles during the wter wsh opertion. spryed t 250 litres/minute. Detergents re used in Seven low pressure wter nozzles hve been permnently instlled in the diffuser cse. An enlrged drin clening the compressors. Wter wsh will restore the engine performnce pipe ws fitted to the bottom of the free turbine exhust elbow. close to clen engine condition. However, some of the deposits cnnot be removed, nd the engine performnce 4. A spre gs turbine ws purchsed nd the will be grdully deteriorted s cn be verified from spre prts stock doubled. the monitoring prmeters shown in Fig. 10. SUMMARY C Nl N2 - y- 2 u c E 3 C 2 w 1 TT7 0 cc G FF 0 TET since lst workshop repir (hrs) Fig. 10 Deteriortion of n engine performnce during 3 weeks opertion. The performnce cn be restored only by clening the engine t workshop. Tble 5 RUNNING HOURS 1. On the bsis of our experience during the summer (over 4,000 engine hours) we re ble to confirm tht opertion with blended fuel oils fulfilled our expecttions, in other words, the relibility of the ship ws mintined nd profitbility improved t lower fuel outly. 2. The period between engine exchnges is now reduced to hours, the min problem being clening of the turbine 1st stge nozzle guide vnes becuse deposits cnnot be entirely removed with the present wshing system. Thus the efficiency of the turbine will grdully diminish. For this reson it is economiclly fesible to dismntle the turbines nd clen them with high pressure wsh t lest every 4 weeks. Lst summer we crried out 12 engine exchnges nd the longest period between removls ws 740 hours or 5 weeks. 3. In ddition to turbine clening in our workshop, mintennce work ws incresed due to fuel nozzle clenings nd combustion chmber repirs. The fuel nozzle hd to be clened every 700 hours becuse of the mgnesium dditive coking problem (see under Mgnesium dditives). Blockges in the fuel nozzles cused burning dmges on combustion chmber wlls which hd to be ptch repired more often thn before. 4. The oil soluble mgnesium dditives prevent vndium corrosion t rtio of Mg/V = 2.0. Gs Turbine Totl Time Totl Time Free Turbine Totl Time Totl Time Seril No. with BFO Seril No. with BFO , SB ,398 2, , BB ,494 2, , BB , ,032 1,393 SB ,310 1,242 TOTAL: 49,439 4,388 TOTAL: 49,439 4,388 8

9 5. The three stge demisters keep the suction ir slt content below the llowble limit (0.05 p.p.m.) 6. The fuel system operted quite stisfctorily, except tht the Mg-dditive coking problem cused blocking of doublex fuel filters so rpidly tht the filters hd to be clened twice dy. After the coking problem hd been solved, the sitution improved considerbly. In order to get resonble service time for the fuel filters, we intend to double the filter cpcity before next summer. 7. Bsed on the experience gined so fr the mximum increse of expenditures for the yer 1982 is predicted below in Tble 6. Tble 6 Cost fctors Fuel heting 2 Mg-dditive 4 GG-mintennce 5 GG-lesing 3 GG-spre prts 2 Totlly: 16 Incresed expenditure USD/BFO ton The fuel consumption hs incresed bout 2.8 % due to lower het vlue of blended fuel oil, nd bout 2 due to turbine fouling. The deslting of residul fuel t refinery costs bout USD 35/BFO ton. The blend used tody consists of 23 % distillte nd 77 residul fuel. Bsed on the November 1981 prices (distillte USD 319/ton nd residul USD 185/ton) the svings per ton of blended fuel oil were bout USD 65. DIESELS FOR WINTER TRAFFIC The use of diesel-electric mchinery is intended to improve Finnjet fuel economy during the low seson when speed nd power requirements re t their lowest. Under these conditions the gs turbines re t their lest efficient. When high speed is required, gs turbines still offer the economicl lterntive becuse of their compct size nd low weight; this is of prticulr importnce or pssenger vessel, nd for this reson the gs turbines will continue to be employed during the busy seson when voyge time of 22.5 hours hs to be mintined. The new power plnt will comprise two diesel-electric engines with n output of 5,700 kw ech. These will be coupled to genertors of 6,500 kva cpcity of 800 r.p.m, These genertor sets will he plced in two seprte engine rooms to be built into the ft prt of the cr deck. The genertors will drive two propeller motors which will be plced in the turbine rooms. The propeller motors will be coupled to the originl reduction gers vi SSS-type clutch nd n dditionl two-wheel reduction ger. The genertors nd propeller motors will be wter cooled. when using the diesel engines the vessel speed will be bout 18.5 knots, nd the crossing time between Helsinki nd Trvemunde will be bout 36 hours. The use of hevy fuel, to be burnt in the new, medium-speed diesel engines, together with their low specific fuel consumption compred with the low efficiency utilistion of the gs turbines, will improve Finnjet fuel economy mrkedly during the low seson. Fuel consumption on 36-hour one-wy voyge, using the diesel engines, will drop by bout 50 7, lthough over the yer the fuel sving chieved through the use of the diesel engines will only be bout 15 %. iy 6 T, I^- 2 1 TL 1 = Diesel engine 2 = Genertor 3 = Electric motor 4 = Additionl reduction ger + clutch 5 = Diesel engine exhust gs piping 6 = Diesel engine ir inlet 7 = Control equipment for the diesel-electricl mchinery -_- r:j Fig. 11 Generl rrngement of the Finnjet diesel-electricl mchinery 9

10 GTS FINNJET - TECHNICAL DETAILS Gs turbine mch Min dimensions: Length, o.. Length, W.L. Bredth Drught Drught t propeller Depth to the 4th deck Depth to the 7th deck Displcement Gross tonnge Net tonnge Speed Dedweight m m 25.4 m 6.5 m 7.2 m 14.8 m 23.2 m bt. 16,500 m 3 bt. 65,000 m 3 (24,605 register tons) 3 bt. 32,500 m (10,786 register tons) 30.5 knots 2,825 tons Pssenger cbin spces: A-cbin, berths B-cbin, 2 berths C-cbin, 4 berths Lounge chirs Pssenger cpcity Crgo cpcity: Free height on cr deck Free bredth t bow rmp Free bredth t stern rmp Crgo lterntive A: Crgo lterntive B Crgo lterntive C 12 m cbins 8 m cbins 4 m 74 cbins 268 1, m 4.5 m 5.0 m Lorries 34 Buses 4 Crs 140 Lorries 23 Buses 5 Crs 225 Crs Gs turbine 2. Air inlet chmber 3. Air filters (demisters) 4. Bypss chnnel 5. Air vent nd sound dmpers 6. Exhust vent nd sound dmpers 7. Reduction ger 8. Disengging couplings 9. Vrible pitch propellor 10. Pitch control device FT 4C-1DLF gs turbine Gs genertor I Power turbine Propulsion mchinery 2 gs turbines, Prtt & Whitney FT4C-1DLF Output: Rte of revolution: Fuel consumption: 2 x 27.. MW (2 x 37,500 hp) 63.3 m (3,800 r.p.m.) 274 kg/mwh (200 g/hph) 2 reduction gers, Lohmnn & Stolterfoht GUY 7733, 2-step, equipped with 2 disengging couplings Reduction rtio: 2 controllble pitch propellors, KMW 179 s 1/4 Dimeter: Rte of revolution: A Air inlet B Low-pressure compressor C High-pressure compressor D Combustion chmbers : 1 E High- nd low-pressure turbines F Power turbine (free turbine type) G Exhust outlet H Power tke-off 5.0 m 2.85 s 1 (171 r.p.m.) Computer control of the gs turbine nd mesuring nd lrm equipment by AEG Schiffbu 10

11 CONCLUSIONS Development of pssenger trffic Finnlines formerly hd two vessels in service on this route, nd in 1976 the two ships together crried 73,000 pssengers. Finnjet hs crried 817,000 pssengers during the lst four yers, nd for exmple in 1979 the number of pssengers ws 237,000 nd dditionlly 30,300 vehicles were crried. In summertime bout 75 2 of the trvellers re from Centrl Europe. The ship operted t cpcity of 75 % in 1980, nd in the summer of 1981 n bout 85 2 utilistion of the ship's cpcity ws reched. This corresponds to n verge of 1,200 pssengers per deprture. Gs turbines The experience gined in operting gs turbines over the lst four yers hs been quite stisfctory nd completely fulfilled our expecttions from the opertionl relibility nd mintennce spects. However, we re not stisfied with the high fuel costs incurred in operting t low speeds during off seson so tht the use of light distillte in the gs turbines hs not been economicl. Fuel economy The only rel problem tht we hve encountered with Finnjet hs been the fuel economy. To improve this spect of opertion, the less expensive blended fuel oils hve been used since the beginning of summer Also the ship's schedules were reorgnised in ccordnce with overll expenditure so tht the number of journeys hs been reduced by 44. Thus in 1982 bout 220 one-wy journeys will be mde. When the diesel engines ordered for off seson opertion re instlled in the utumn of 1981, the CODEOG Finnjet (combined diesel or gs turbine) will be equipped to keep pce with the chnges in pssenger trffic requirements s well s possible. 11