Techno Tec hnology logy rev review iew
2
Tech Te chno nolo logy gy Re Revi view ew This is a brief guide to the technical features and benefits of the Sulzer RTA84T-B and RTA84T-D low-speed marine diesel engines, herein collectively called Sulzer RTA84T engines.
Introduction
4
Development background
6
Exhaust emissions
7
Real in-service fuel economy
8
Piston-running behaviour
10
Engine structure
12
Running gear
14
Combustion chamber
16
Fuel injection and valve actuation
18
Turbocharging and scavenge air system
20
Installation arrangements
21
Maintenance
22
Main technical data
23
3
Introduction The Sulzer RTA84T low-speed marine diesel engines are tailor-made for the economic economic propu propulsion lsion of very large large crude crude oil tankers tankers (VL (V L CC CCss and ULCC UL CCs). s). In this t his role, they offer clear, substantial benefits:
Optimum Opt imum power power and speed
Competit Competitive ive first cost
L owest owest possible fue fuell consumption over the t he whole whole operati operating ng range from full speed speed to ‘slow steaming’
Three years’ time between overhauls
L ow maintenance maintenance costs through thr ough reliability reliability and durabilit durability y
F ull compli complianc ance e with with the IMO IM O N O X emission reg regulation. ulation.
Whe When the Sulz Sulze er RT RTA84T A84T typ type was initia initiate ted d in 1990 1990,, larg large e tank tanke ers had had beco become me standa standardised rdised in size, based on standard standard parcel sizes of multiples of a million barrels (bbl). This has led to the deadw deadweight eight capacity capacity of a VL V L CC (about (about tw t wo million bbl) being around around 285,000 tonne t onness at design draught draught and 300,000 tonnes at scantling scantling draught and in some cases going up to 320,000 tdw.
First Sulzer RTA84T-B being completed in September 1997
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For newbuildings of 285,000 tdw (design), the average installed power needed is around 27,000 kW (36,000 bhp) for a ship’s service spe speed ed of of around 15.5 knots. knots. The T he usually usually selected selected propeller propeller speed speed of some 70 to 79 rev/min rev/ min is a direct resu r esultlt of aiming for an ‘optimum propulsion’ installation within the widely accepted MARPOL recommendation recommendation for for the t he selection selection of propeller propeller diameters. diameters. These T hese considerations for for VL CC ne newbuil buildi ding ngss led led to the parame ramete ters rs of the Sulz Sulze er RT RTA84T A84T engin ngine e.
Principal particulars RTA8 RTA84T 4T-B -B RTA8 RTA84T 4T-D -D
Type Bore
mm
840
840
Stroke
mm
3150
3150
Output, R1
kW/cyl bhp/cyl
3880 5280
4100 5880
Speed range, R1–R3
rpm
74–59
76–61
BMEP at R1
bar
18.0
18.5
Pmax
bar
140
144
Mean piston speed at R1
m/s
7.77
8.0
5– 9
5–9
Number of cylinders BSFC for low-port version: at full load, R1
g/kWh g/bhph
168 123
168 123
at 85% load, R1
g/kWh g/bhph
164 121
164 121
at 70% load, R1
g/kWh g/bhph
163 120
163 120
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Develo Dev elopme pment nt bac backgr kgroun ound d Wärtsi Wärtsilä lä has has a polic olicy y of conti continu nuou ousl sly y updatin dating g its engin ngine e desig signs to adap dapt them them to the latest market requirements requirements and to incorporate incor porate the benefit benefitss of technical improvements. improvements. The T he Sulzer Sulzer RT R T A 84T engine engine type has followed followed this policy since it w was as introduced in May 1991. In 1996, the modernised version B of the RTA84T was introduced, with many new design design fea f eatures tures for f or easier easier manufacturing manufacturing and improved service behaviour. behaviour. There T here wa was no cha change nge in powe ower outp outpu ut. In July 1998, the t he fuel consumption consumption of the version B could be improved by 2 g/kWh g/ kWh by the applica application tion of ‘low port’ cylinder cylinder liners in which which the the scaveng scavenge e air air inlet inlet ports ports have a reduced reduced height, height, in in combination with turbocharge turbochargers rs of higher higher eff ef ficiency. iciency. T he result result is a full-loa f ull-load d fuel consum consumption ption of 168 g/kWh g/ kWh (123 (123 g/bhp g/ bhph) h) for R 1-rated engines. At the end of 1998 1998,, the powe ower outp outpu ut of the RT RTA84T A84T was incre increaased sed in the versi version on D to t o 4100 kW/cylinde kW/ cylinderr (5580 bhp/cylinde bhp/ cylinder) r) at 76 rev/min. rev/ min. This was was in response response to a market market req r equireme uirement nt for f or higher VL V L CC service speeds speeds to give owners owners and charterers greater flexibility flexibility in economica economicall ship operati operation on to suit the wide wide variations in charter/ freight rates rat es at at that t hat time. time. The power power available available from fr om a seven-cylinde seven-cylinderr engine wa was there thereby by incre increaased sed from 27,1 27,160 60 to 28,7 28,700 00 kW (36,9 36,960 60 to 39,0 39,060 60 bhp bhp).
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Exha Ex haus ustt em emis issi sion onss With With the curre current nt popu opular lar conc conce ern abou bout the the enviro nvironm nme ent, exha xhaust gas emiss missio ions ns have become an important aspect of marine diesel engines. T oday, oday, the control control of N O X emissions in compliance with Annex VI of the M A R POL PO L 73/ 78 convention convention is standard standard for for marine diese diesell engine engines. s. For For Sulzer R T A 84T engines, engines, this is is achieved achieved wit without hout adding any any extr extraa equipme equipment nt to the engines. engines. Instead, Instead, NO N O X emissions are are reduced reduced below the limit set by the MA MAR R POL PO L regulati regulation on by L ow N O X Tuning techniques, techniques, involving a careful combination of adapted adapted compression ratio, inj injection ection and valve valve timing, and dif diffferent fue fuell nozzles to achieve the best best results. Low L ow N O X Tuning is simple and eefffective yet yet assures high engine engine reliability and also keeps the fuel consumption at the lowest possible level. As furthe further reg regulatio lations ns to contro controll othe other emiss missio ions ns and furthe further low lower the N O X limit are fully expected, expected, Wärtsilä Wärtsilä is carrying carrying out out a long-term rese r esearch arch programme to develop develop techniq technique uess for f or reducing exhau exhaust st emissions, including N NO O X , SO X , CO2 and smoke.
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Real Re al in in-s -ser ervi vicce fu fuel el ec econ onom omyy Sulzer RTA84T engines have a particularly low fuel consumption right across their load/spe load/ speed ed range. range. This T his is advantageo advantageous us for f or large tankers tankers which are called upon upon to operat operate e over over a wide range range of ship speeds, speeds, from fr om full full speed speed to ‘slow steaming’, whe whethe therr fully fully-lo -loaaded ded or in ball ballaast. With With ‘low ‘low-port’ -port’ line liners, rs, RT RTA84T A84T engin ngine es now now exceed exceed 50 per cent thermal t hermal efficiency eff iciency at at full power, power, and even even more at part load. An imp important ortant contri contribu butio tion n to the fuel fuel econo conomy my of the RT RTA84T A84T engin ngine es is their their improved level level of setting setting flexibility flexibility compared compared with with other engine types. types. This T his is given by a combination combination of of V E C (Varia (V ariable ble E xhaust xhaust valve Closing) and and VIT VI T (Variable Injection Timing). Together, these permit a more comprehensive optimisation of the engine’s working process for reduced fuel consumption over the whole load range. T he VIT VI T improves engine engine ef efficiency in the the uppe upperr load range by maintaining the maximum maximum cylinder cylinder pressure pressure at at the full-load f ull-load value by by injection timing timing advance advance.. The T he VE C sy system stem is emp mplo loy yed in the mid mid loa load rang range e to incre increaase the effectiv ffective e comp compre ress ssio ion n ratio ratio and and thereby lower lower fuel consumption. consumption. The T he V E C system is a straightf str aightforwa orward rd adaptation adaptation of the hydraulic hydraulic actuation system system of the t he exhau exhaust st valve valve so that the t he hydraulic pressure can be released earlier than usual. The ‘low port port’’ cylinder liners combined with with higher higher eff ef ficiency turbocharge turbochargers rs give an overall reduction in fue f uell consumption. There T here is no penalty penalty in either higher component component temperatur temperatures es or too t oo low exhau exhaust st gas temperat temperatures. ures. The T he low port portss give a longer longer effective eff ective expansion expansion stroke stroke in the cycle. cycle.
BSFC [g/kWh]
BSFC [g/bhph] 126.4
172 Without VIT/VEC
123.5
168
120.5
164 With VIT/VEC
117.6
160
114.7
156 50
60
70
80
90
100
Engine Load, % Influence of variable fuel injection timing (VIT) and variable exhaust valve closing (VEC) on part-load fuel consumption of RTA84T-B and RTA84T-D engines. For maximum continuous rating R1 with low ports.
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oil supply
compressed air
control
Hydraulic actuating arrangement for the exhaust valve. Variable exhaust valve closing (VEC) is provided by a control valve which opens to release the pressure of the hydraulic ‘push rod’ early thereby allowing the exhaust valve to close early.
Cylinder pressure 100% load Part load with VEC Part load without VEC
Exhaust valve lift 100% load, or part load without VEC Part load with VEC
BDC
TDC crank angle
Exhaust valve lift and cylinder pressure on a common scale of crank angle to show the influence of VEC. With earlier closing of the exhaust valve at part load (dotted curve), the the cylinder pressure peak rises higher than if a fixed exhaust valve timing is used (solid line).
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Piston Pis ton-ru -runni nning ng beh behavi aviour our Today the time between overhaul (TBO) of low-speed marine diesel engines is largely determined by the piston-running piston- running behaviour behaviour and its it s effect eff ect on the t he wea wearr of piston rings and cylinder liners. For this reason, Sulzer RTA-series engines now incorporate incorporate TriboP TriboPack ack technology - a package package of design design measures measures that enable enable the T BO of the cylinder cylinder components, components, including piston ring ring renewal, renewal, to be extended extended to at least least three t hree yea years. rs. At A t the t he same same time, TriboPack TriboPack allows allows the furt f urther her reducti reduction on of cylinder cylinder lubricating lubricating oil fee f eed d rate. T he design design measures measures incorporated in TriboP T riboPack ack are: are:
Multi-level cylinder lubrication
L iner of the t he appropriat appropriate e material, material, with with suff suf ficient hard phase phase Careful Caref ul turning of the liner running surf surface ace and dee deep-honing p-honing of the t he liner liner over the t he full length of the running surface surface
M id-stroke id-st roke liner insulation, and where where necessa necessary, ry, insulating tube t ubess in the t he cooling bores in the upper upper part of the liner
Pre-profiled piston rings in all piston grooves
Chromium-ceramic coating on top piston ring
RC (Running-in Coating) piston rings in all lower piston grooves
Anti-Poli Anti-Polish shin ing g Ring (APR) APR ) at the top of the cyli cylind nde er line linerr
Increased ncreased thickness of chromium chromium layer layer in the piston-ring piston-r ing grooves.
Liner insulation
Anti-polishing ring
Multilevel lubrication
Cr-ceramic pre-profiled top piston ring
Mid-stroke insulation
Lower rings pre-profiled and RC-coated
Liner fully deep honed
Thick chromium layer
Design measures included in Sulzer TriboPack. Together they give improved piston-running behaviour for three years’ between overhauls and lower cylinder lubricant feed rates
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A ke key eleme lement nt of TriboPa TriboPack ck is the deep-hone -honed d line liner. r. Care Careful ful mach machin inin ing g and dee deep honing gives gives the the liner liner an ideal ideal running surface surf ace for the t he pist piston on rings, toge t ogether ther with an optimum surface microstructure. The Anti-Polishing Ring prevents the build up of deposits on the top land of the piston which can damage the oil film on the liner and cause bore polishing. I t is is also important important that that the t he liner liner wall temperatur temperature e is adapted adapted to keep keep the liner surface surf ace above the dew point temp t emperature erature througho thr oughout ut the t he pist piston on stroke str oke to avoid cold corrosion. corr osion. The T he load-depe load-dependen ndentt cylinder cylinder liner cooling system plays plays an important important role r ole in ensuring opti optimum mum temperature temperature control contr ol over the the load load range. range. Mid-st M id-stroke roke insulati insulation on and, where necessary, insulating tubes are employed to optimise liner temperatures over the piston stroke. Whil Whilst st tryin trying g to avoid void corros corrosiv ive e wear by optim optimis isin ing g line linerr wall temp tempe eratur rature es, it is necessary to keep as much water as possible out of engine cylinders. Thus, the highly-e highly-effficient vane-t vane-typ ype e water water separa separators tors fitted fit ted in RT R T A 84T engine enginess after aft er the scavenge air cooler and the effective water drainage arrangements are absolutely essential essential for f or good piston running. L oad-depe oad-depende ndent nt cylinder cylinder lubrication is provided provided by the well-proven well-proven Sulzer multi-leve multi- levell accumulator accumulator system which which provides the timely quantit quantity y of lubricating lubricating oil for good piston-running. The lubricating oil feed rate is controlled according to the engine load and can also be adjusted according to engine condition.
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Engi En gine ne st stru ruct ctur uree
Partially erected engine comprising cylinder block with cylinder liners on top of the column.
Sulzer RTA84T engines have a well-proven type of structure, with a ‘gondola’-type bedplate surmounted by very rigid, A-shaped double-walled columns and cylinder blocks, all secured secured by pre-tensioned ve vert rtical ical tie tie rods. The T he whole whole structure structure is very sturdy sturdy wit with h low stresse str essess and high stif st ifffness. Both bedplate bedplate and columns columns are welded welded fabrications which are also designed designed for f or minimum machining. machining. A hig high h structu structura rall rigid rigidity ity is of major major imp importanc ortance e for the engin ngine e’s long long strok stroke. Accord Accordin ing gly the desig sign is base based d on extens xtensiv ive e stress stress and deforma formation tion calc calcu ulatio lations ns carried out by using a full three-dime t hree-dimensional nsional finite-eleme finite-element nt computer model for for different column designs to verify the optimum frame configuration. The cylinder cylinder jacket is assembled assembled from from individual cast-iron cast-i ron cylinder blocks, bolted together to t o form form a rigid rigid whole. whole. The fue f uell pumps pumps are carried on one side of the 12
cylinder jacket and the scavenge air receiver on the other. Access to the piston underunder-side side is normally from from the fue f uell pump side, but is also possible from f rom the t he receiver receiver side of the t he engine engine,, to to allow for maintenance maintenance of the piston rod gland aand nd also for inspecti inspecting ng piston rings. The tilting-pad thrust bearing is integrated in the t he bedpla bedplate. te. Ow O wing to the use of gear gear whee wheels ls for f or the t he camshaft camshaft drive, the thrust thr ust bearing can be very short and very stif stiff, and can can be carried in a closed, closed, rigid housing.
The compact arrangement around the thrust bearing which acts on the flange of the main gear wheel located here on the crankshaft.
Crankshaft installed in the bedplate of a
The complete, pre-fitted cylinder block being lifted and
seven-cylinder engine.
mounted on the engine column. column.
13
Runn Ru nnin ing g ge gear ar T he running gea gearr comprises the t he crankshaft crankshaft,, connecting rods, pistons and pist piston on rods, together with their t heir associated bearings bearings and piston rod rod glands. glands. T he semi-built semi-built cranksha crankshaft ft of the t he RTA RT A 84T engine engine has to cater cater for f or the t he longe longest st stroke str oke ever ever used in a Sulzer engine. engine. To T o limit the crankshaft weight eight for f or production, assembly assembly and transport, transport , the t he main journals and crank cr ank pins pins are bored bored.. T he design design of the crank crank has has a good transve transverse rse width at the t he uppe upperr part of the web, web, allowing allowing the web web to to be slim longitudinally. The The favourable torsional torsional vibration vibration characteristics characterist ics allow six-cylinder six-cylinder engines engines to use a viscous dampe damperr for many cases cases instea instead d of a Geislinger damper. damper. The main bearings have white metal shells. The main bearing caps are held down
Crankshaft of a seven-cylinder engine
by a pair pair of jack bolts bolts for f or easy assembly assembly and dismantli dismantling ng of bearings. bearings. A be better tter unde nderstand rstandin ing g of the main main bea bearing ring loa loads is obta obtain ine ed with toda today’s f inite-ele inite-element ment analysis and elasto-hydrodynamic elasto-hydrodynamic calculation techniq t echnique uess as they take take into account the structure around the bearing and vibration of the shaft. The FE model model comprises the complete complete shaft and its bearings together wit with h the surrounding surrounding structure. Boundary conditions, including the crankshaft stiffness, can thus be fed into into the bearing bearing calculation. The crosshead crosshead bearing bearing is designed designed to the t he same same principles principles as for all other RT R TA engines. engines. It It also fea featur tures es a full-w full-width lower lower half bearing. bearing. The T he crosshead crosshead bearings bearings have thin-w thin- walled shells shells of white metal for f or a high load-bearing load-bearing capacity. Sulzer low-speed low-speed engines engines retain the t he use of a separate elevated-pressure elevated-pressure lubricating oil supply supply to the crosshead. It provides hydrostatic lubrication which lifts the crosshead pin off the shell during during every every revolution to to ensure ensure that suff sufficient icient oil film f ilm thickness is maintained under under the gas load. This has proved crucial to long-term long-t erm bearing bearing security. securit y.
14
top shell Max oil pressure
bottom shell
0
> 500 bar
Fore
S X E
S X E
Aft
S P F
Min oil film thickness
> 20 m
0
FPS
Fore
S X E
EXS
S X E S P F
WM stress
<4
S X E
> 20 N/mm2
Fore S X E
Aft Example of main bearing calculation showing (right) orbit of journal, and above the maximum oil pressure distribution, minimum oil film thickness, and white metal stress.
E xtensive developme development nt work has been been put into the piston rod r od gland because because of its its importance import ance in keeping keeping crankcase oil consumption down to a reasonable level and maintaining the qualit quality y of the t he system system oil. T oday’s oday’s RT R T A engines engines employ employ an improved design design of piston rod r od gland with with gas-tig s-tight top scra scrap per ring rings, and large drain areas and channels. Harde Hardened ned pist piston on rods are now standard to ensure long-term stability in the gland behaviour.
Jack bolts for holding down the main bearing caps in place in the prefitted column ready ready for mounting on the bedplate
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Combus Com bustio tion n cha chamb mber er T he combusti combustion on chamber chamber in in today today’s ’s diesel diesel engine has a major major influe inf luence nce on the engine’s reliability. Careful attention is needed for the layout of the fuel injection spray patt pattern ern to to achieve moderate moderate surface surf ace temperatures temperatures and to avoid carbon deposits deposits.. However, the large stroke-to-bore ratio of the RTA84T allows a relatively deeper combustion chamber chamber with more freed freedom om in the layout layout of the fue fuell spray patt pattern. ern. Low L ow component component temperatur temperatures es are also also desirable to give more freed f reedom om for f or rea r eaching ching low N O X emissions. At Wärtsi Wärtsilä lä,, optim optimis isaation tion of fuel fuel inje injecti ction on is carrie carried d out out first first by the use of mode modern rn calculati calculation on tools, such such as CFD CF D (computerised (computerised fluid fluid dynamics) dynamics) analy analysis. sis. The T he calculated calculated results are then confirmed on the first test engines. T he well-proven well-proven bore-cooling principle principle is also employ employed ed in all the t he combusti combustion on chamber chamber components to control contr ol their their temperatur temperatures, es, as as well well as thermal thermal strains and mechanical mechanical stresse str esses. s. The solid forged forged steel, steel, bore-cooled bore-cooled cylinder cylinder cover is secured secured by eight eight elastic studs. I t is equippe equipped d wit with h a single, centr central al exhaust exhaust valve in Nimonic N imonic 80A which is housed in 0° 300 200 0 °C 300 400 500 300 200
TDC– Top Ring 0 °C 100 200
100 200 300 °C Surface temperatures measured on the combustion chamber components of the RTA84T-B at full-load R1 rating. The thickness of the lines represents the circumferential variation in temperature.
16
Computer simulation of fuel injection spray patterns from the three nozzles of the RTA84T-B to illustrate that the main concentrations in the sprays keep away from the chamber surfaces. surfaces.
a bolted-on valve cage. The RTA84T has three fuel injection injection valves symmetrically symmetrically distribut dist ributed ed in the cylinder cylinder cover. AntiA nti-corr corrosion osion cladding is applied applied to the cylinder cylinder covers downstream of the injection nozzles to protect the cylinder covers from hot corrosive or erosive attack. T he piston of the t he R T A 84T comprises comprises a forge for ged d steel steel crown with a short skirt. Combined jet-shaker oil cooling of the piston crow crown n provides opti optimum mum cooling perf performance. ormance. It gives very very moderate moderate temp t emperatures eratures on the piston crow cr own n wit with h a fairly fairly even even temperature temperature distribution distr ibution right across the the crown crown surface surf ace.. No N o coatings are necessa necessary. ry. The cylinder cylinder liner is also bore cooled. cooled. Its Its surf surface ace temperatures are optimised by having a higher coolant entry point so that t hat less of the liner is cooled, ap applying plying an insulation bandage bandage around around the outside outside of the t he liner liner in the t he upper mid-stroke region and, where necessary, by employing employing insulation insulation tubes in the t he cooling bores.
Cylinder liner with the standard mid-stroke insulation in the form of a Teflon band retained by stainless steel cladding.
17
Fuel injection and valve actuation T here are are three thr ee uncooled uncooled fue fuell injection inj ection valv valve es in each cyli cylind nde er cove cover. r. Their Their nozzle tips are sufficiently long that the cap nut is shielded by the cylinder cover and is not exposed exposed to the t he combusti combustion on space. T he camsha camshaft ft-driven -driven fue f uell injec inj ection tion pumps are of the well-proven double-valve double-valve controlled contr olled type that has been been traditional traditional in in Sulzer Sulzer low-speed low-speed engines. Injection timing is controlled by separate separate suction suction and spill valve valvess regulated regulated through through eccentr eccentrics ics on hydraulically-actuated hydraulically-actuated lay shafts. shaft s. Consequently, Consequently, great flexibility flexibility in timing timi ng is possible through thr ough the variable fuel injection timing (VIT (VI T ) system system for improved part part-load -load fue f uell consumption, and for the t he fuel fuel quality quality setting (FQS) (FQ S) lever lever to t o adjust the injection timing according to the t he fuel oil qualit quality. y. The valve-controlled fuel injection pump, in comparison with a helix type, has a plunger with a significantly greater sealing sealing length. The T he higher higher volumetr volumetric ic efficiency eff iciency reduce reducess the torque torque in the camsha camshaft ft.. Additiona A dditionally, lly, injection injection from f rom a valv valve e-contro -controll lle ed pump is far more more stabl stable e Fuel injection valve. The nozzle is not exposed to the combustion thereby avoiding material burning off at very low loads loads and rotational rotational shaft speeds speeds down down to to 15 per cent of the rated rated speed are achieved. Valve control also has benefits of less deterioration of timing timing over the years years owing to less less wea wearr and to freed f reedom om from from cavitation. cavitation. T he camshaft camshaft is assembled assembled from from a number of segments, segments, one for each each pump housing. The segments segments are connected connected through thr ough eit either her flange flange-t -typ ype e couplings couplings or SK F sleeve sleeve couplings. couplings. E ach segment segment has an integ integral ral hydraulic reversing servomotor located within the pump housing. The camshaf camshaft drive uses the wellwell-proven proven Sulzer arrang arr angeme ement nt of gear gear wheels wheels housed housed in a double column column located at the the driving end or in tthe he centr centre e of the t he engine engine..
18
Pump housings. Each combines fuel injection pumps and exhaust valve actuator pumps for one pair of cylinders
There are are four f our gear gear wheels wheels in the t he camshaft camshaft drive. The main gear wheel on the crankshaft is in one piece and flange-mounted.
Fuel injection pump with double control valves
19
Turb Tu rboc ocha harrgi ging ng an and d sc scaave veng ngee ai airr sy syst stem em T he RTA RT A 84T is uniflow scavenge scavenged d with with air inlet ports in the lower lower part part of the cylinder and a single, centr central al exhaust exhaust valv valve e in the cyli cylind nde er cove cover. r. Scave Scaveng nge e air is deli delive vere red d by a constant-pressure constant- pressure turbocharging system system with one or more high-efficiency high-eff iciency exhau exhaust st gas turbochargers depending depending on the the numbers numbers of cylinders. cylinders. For F or starti st arting ng and and during during slow-running, the scavenge air delivery is augmented by electrically-driven auxiliary blowers. The scavenge scavenge air air receiver receiver is of simplified simplified design design and modest modest size size wit with h integral non-return non-return flaps, f laps, air air cooler, and the auxiliary auxiliary blowers. blowers. T he turbochargers are mounted on the t he scavenge scavenge air receiver receiver which also also carries the the fixed foot f or the t he exhaust exhaust manifold. I mmediately mmediately after after the the cooler, cooler, the scavenge scavenge air passes passes through thr ough a highly-efficient highly-eff icient water water separator which comprises a The scavenge air receiver assembly mounted on the side of the cylinder cylinder block. row of vanes vanes which divert divert the air flow f low and and collect the t he water. water. It is complete with the scavenge air There are ample ample drainage provisi provisions ons to t o remove remove completely completely bends, auxiliary blowers and air coolers. the condensed condensed water water collected at the t he bottom of the separator separator.. This arrangement arrangement provide providess the effective eff ective separation separation of condensed condensed water from f rom the the stream of scavenge scavenge air air which is imperati imperative ve for satisfactory satisf actory piston-running piston-running behaviour. behaviour.
Simulation by computer fluid dynamics (CFD) of the air flow velocities through the 90-degree bend in the scavenge air duct and the cooler.
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Instal Ins tallat lation ion arr arrang angeme ements nts Sulzer RTA-series engines have specific design features that help to facilitate shipboard installation. The broad layout layout fields f ields of the t he Sulzer RT RT A engines engines gives gives the ship designer designer ample ample freedom to match the t he engine engine to the t he optimum optimum propeller propeller for f or the t he ship. T he RTA RT A engines engines have simple seating seating arrang arrangeme ements nts with a modest modest number number of holding down down bolts bolts and side stoppers. Only eight side stoppers are required for a seven-cylinder RTA84T. No end stoppers, thrust brackets brackets or fitt f itted ed bolts are neede needed d as thrust transmission tr ansmission is provided by thrust thr ust sleeves sleeves which which are applied applied to a number number of the holding-down holding-down bolts. The holes holes in the the tank top for the thrust thrust sleeves sleeves can be made by drilling or even even flame f lame cutting. cutt ing. Af A fter alignment of the bedplate, bedplate, epoxy epoxy resin chocking chocking material is poured around the thrust thr ust slee sleeves. ves. All ancil ncilla larie ries, s, such such as pump mpss and tank tank cap capacitie cities, s, and their their arrang rrange ement ment are optim optimis ise ed to redu reduce ce the installation installation and operati operating ng costs. The T he number number of pipe connecti connections ons on the t he engine engine that must be connected connected by the shipyard shipyard are are minimised. The engine’s engine’s electr electrical ical power power req requireme uirement nt f or the t he ancillary ancillary services is also kept kept down to a minimum. Sulzer RT R T A engines engines have a valuable valuable waste waste heat heat recovery potential to generate generate steam for heating heating services services and for a turbogenerator. A sta stand ndaard all-e ll-ele lectri ctricc inte interfac rface e is emp mplo loy yed for engin ngine e mana manag gement ment syste systems ms - know nown as DE N IS (Diesel Engine E ngine I nterface nterf ace Specification) Specificat ion) - to meet meet all needs needs for control, control, monitoring, monitoring, saf saf ety and and alarm alarm wa warning rning functi function ons. s. This match matche es remo remote te contro controll syste systems ms and ship ship contro controll syste systems ms from a numb numbe er of approved suppliers. T he engine engine is equipp equipped ed with with an integrated axial axial detuner at the t he free fr ee end of the t he crankshaf crankshaf t. A n axial detuner detuner monitoring monitoring system develope developed d by Wärtsilä Wärt silä is standard equipment. equipment. Compensation Compensation for f or second-order forces f orces and moments moments can be provided b by y eit either her one or both of a gear-dr gear-driven iven Lanche L anchest ster er balancer balancer at the driving driving end of the t he engine engine and and an electr electrically-driven ically-driven balancer balancer at the t he free end.
Thrust
Thrust Side Side stopper stopper
Side Side stopper stopper Thrust Thrust bracke brackett
Arrangements for transmitting propeller thrust to the engine engine seatings. The inset shows the thrust sleeve for the the thrust bolts.
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Maintenance Primary Pr imary objectives in the design design and developme development nt of Sulzer RT R T A engines engines are are high reliability and long times between overhauls. Three years between overhauls are now being achieve achieved d by engine enginess to t o the the latest design standa standards. rds. At A t the same time, their hi high gh reliability gives shipowners more freedom to arrange maintenance work within ships’ sailing schedules. Yet, Yet, as main mainte tena nanc nce e work is inevitable, particular attention is given to ease of maintenance by including tooling and easy easy access, and by providing providing easy-to -understand instructions. F or example example,, all major fastenings f astenings througho thr oughout ut the engine are hydrau hydraulically lically tightene tightened. d. Access Access to the crankcase continues to be possible f rom both both sides of the engine. engine. The T he handling handling of components components within ithin the t he crankcase crankcase is facilitated acilitated by ample ample provision for f or hanging hanging hoisting equipme equipment. nt. Att A ttention ention to design details also allows simpler dismantling procedures. procedures.
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Main Ma in te tech chni niccal data Main data: Version D Cylinder bore
840 mm
Piston stroke
3 150 mm
Speed
61 - 76 rpm
Mean effective pressure at R1
18.5 bar
Piston speed
8.0 m/s
Fuel specification: Fuel oil
730 cSt/50°C 7 200 sR1/100°F ISO 8217, category ISO-F-RMK 55
The RTA84T-B is available at lower power outputs than than the version D shown shown here, and complies with the IMO NO x regulation.
Rated power: Propulsion Engines
Output in kW/bhp at 76 rpm
Cyl.
R1 kW
5 6 7 8 9
61 rpm
20 24 28 32 36
R2 bhp
500 600 700 800 900
R3
kW
27 900 33 480 39 060 44 640 50 220
14 17 20 22 25
bhp
350 220 090 960 830
kW 16 19 23 26 29
19 500 23 400 27 300 31 200 35 100
450 740 030 320 610
R4 bhp
kW
22 350 26 820 31 290 35 760 40 230
14 17 20 22 25
bhp
350 220 090 960 830
19 500 23 400 27 300 31 200 35 100
Power Engine-MCR R1
Engine layout field
Brake specific fuel consumption (BSFC)
g/kWh g/bhph g/kWh g/bhph g/kWh g/bhph g/kWh g/bhph Load 70 %
163
120
160
117
166
122
164
121
Load 85 %
164
121
160
118
165
122
162
119
Load 100 %
168
123
160
118
168
123
164
121
BMEP, bar
18.5
13.0
18.5
5 6 7 8 9
A 8 890 10 390 11 890 14 390 15 890
B 5 000 5 000 5 000 5 000 5 000
C 1 800 1 800 1 800 1 800 1 800
D 11 933 11 933 11 933 11 933 11 933
E 4 4 4 4 4
196 715 715 196 715
F*
G
14 500 2 700 14 500 2 700 14 500 2 700 14 500 2 700 14 500 2 700
R4
R2 Speed
16.2
Principal engine dimensions (mm) and weights (tonnes)
Cyl.
R3
Definitions:
I
K
Weight
760 760 760 760 760
805 805 805 805 805
740 870 990 1 140 1 260
* Standard piston dismantling height, can be reduced with tilted piston withdrawal.
R1, R2, R3, R4 = power/speed ratings at the four corners of the RTA engine layout field (see diagram). R1 = engine Maximum Continuous Rating (MCR). Contract-MCR (CMCR) = selected rating point for particular installation. Any CMCR point can be selected within the RTA layout field. BSFC = brake specific fuel consumption. All figures are quoted for fuel of net calorific value 42.7 MJ/kg (10 200 kcal/kg) and ISO standard reference conditions (ISO 3046-1). The BSFC figures are given with a tolerance of 5%, without engine-driven pumps. The values of power in kilowatts and fuel consumption in g/kWh are the official figures and discrepancies occur between these and the corresponding bhp values owing to the rounding of numbers. ISO standard reference conditions Total Total barometric barometric press pressure ure . . . . . . . . . . . . . 1.0 bar Suction Suction air tempera temperature ture . . . . . . . . . . . . . . . . 25 °C Scavenge air cooling-water temperature. . . 25 °C Relative humidity. humidity. . . . . . . . . . . . . . . . . . . . . . 60%
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s c i h p a r G a s a a W / e c i f f O s ´ k c o B / 4 0 0 2 . 6 0 W
Wärtsilä is The Ship Power Supplier for builders, owners and operators of vessels and offshore installations. We are the only company with a global service network to take complete care of customers’ ship machinery at every lifecycle stage. Wärtsilä is a leading provider of power plants, operation and lifetime care services in decentralized power generation. The Wärtsilä Group includes Imatra Steel, which specializes in special engineering steels. For more information visit www.wartsila.com
WÄRTSILÄ ® and SULZER® are registered trademarks. Copyright © 2004 Wärtsilä Corporation.
Wärtsilä Corporation P.O.Box 196 FIN-00531 Helsinki
Tel: +358 10 709 0000 Fax: +358 10 709 5700
