Technical information. The Power2 performance package NO x down, power up, fuel down

Transcription

1 Technical information The Power2 performance package NO x down, power up, fuel down

2 Power2 two stage turbocharging Leading edge technology for large engine turbochargers. Driven by engine builders demands for ever lower levels of harmful emissions and greenhouse gases combined with ever higher levels of power density and fuel efficiency, Power2 takes turbocharger performance into a new range. 2

3 Even in this early stage of its development, Power2 is already capable of producing pressure ratios up to 8 and more, compared to 5.8 for the best single stage turbochargers. Emissions imperative The launch of Power2 two stage turbocharging comes as the large engine industry gears up for its greatest emissions challenges. A major focus is limitations on oxides of nitrogen (NO x ) due in the middle of this decade.they demand reductions as severe as 80 to 90 % compared with the first stages of the leglisation involved. At the same time, governments all round the world have committed themselves to reducing greenhouse gas emissions, including carbon dioxide (CO 2 ), the major component of engine exhaust gases. Miller enabler Significantly, Power2 two stage turbocharging is already an acknowledged enabling technology of the Miller Cycle, an ingenious method of cooling combustion air to substantially reduce NO x formation in internal combustion engines. It is already in use on large diesel engines designed to meet current rounds of emissions legislation in conjunction with high pressure single stage turbocharging. To meet the stringent future stages of NO x legislation, turbocharging pressure ratios will be needed in the range Power2 is already producing. Boosting efficiency, boosting power The charge air boost pressures two stage turbocharging can produce also bring substantial benefits in terms of engine fuel efficiency. This translates into reduced fuel bills for the engine operator, reduced emissions of the greenhouse gas CO 2 and reduced fossil fuel depletion. In addition, the greater availability of charge air offers potential to raise engine power density. 3

4 Enabling Miller Miller Cycle versus the NO x -SFC trade-off. Taming the trade-off Power2 two stage turbocharging is set to be a major factor in tackling one of the dilemmas of engine emissions reduction the trade-off between NO x formation and specific fuel consumption (SFC). The NOx-SFC trade-off reflects the fact that NO x formation decreases with lower combustion temperatures while fuel efficiency increases with higher combustion temperatures. On diesel engines, a widespread measure has been to reduce combustion temperatures and hence NO x formation by fuel injection rate shaping. Thus, a fuel consumption penalty is incurred in the interests of lower NO x emissions. The Miller Cycle, however, is capable of shifting this compromise into a new, far lower range. Miller Cycle principle On 4-stroke engines, substantial cooling of engine intake air is achieved by shortening the opening period of the inlet valve. This induces expansion and hence cooling in the intake air on the induction stroke. On 2-stroke engines, a similar effect can be achieved by varying exhaust valve closure. The cooling effect is capable of eliminating the combustion temperature peaks responsible for over 90 % of NO x. Power2 pressure ratios versus shorter induction The shorter valve opening periods mean that, without turbo - charging countermeasures, only a reduced mass of air could enter the combustion chamber in the time available. The result would be reduced engine output and poor response to load changes. Higher turbocharging pressure ratios compensate the shorter induction time to avoid combustion air deficiency. [%] Single stage turbocharging Power2 two stage turbocharging inlet exhaust inlet exhaust TDC Specific fuel consumption Strong Miller NO x [%] Emissions Standard inlet valve closure near BDC Induction stroke BDC Miller inlet valve closure before BDC Shifting the curve fuel consumption and NO x reduction potential using two stage turbocharging to achieve strong Miller Cycles on further developed diesel engines. Early Miller Cycle and standard induction at the moment of inlet valve closure. 4

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6 How it works The Power2 two stage turbocharging principle. Intercooling between the two compressor stages reduces the temperature and the volume of the air after the first stage turbocharger which allows the second stage turbocharger to be smaller, making the total system more compact. This arrangement readily produces the high turbocharging pressure ratios needed to create very strong Miller Cycles on 4-stroke medium speed diesel engines. Courtesy Wärtsilä Corporation Achieving the 80 % NO x reduction required by IMO Tier III compliance in ECAs without aftertreatment would reduce the first costs and operating cost of an engine system considerably. Computer simulations using ABB Turbocharging s sophisticated software indicate that this is a realistic prospect. ABB Turbocharging s Power2 concept uses two turbochargers in tandem to create pressure ratios higher than the best single stage turbochargers. Systems under development consist of two specially designed turbochargers of different sizes connected in series. They are tuned as a system to give favorable thermodynamic and mechanical behavior. Their performance is carefully chosen to give the level of air delivery required by the specific appli - cation. The turbine of the smaller turbocharger is located upstream of the turbine of the larger unit in the exhaust gas flow from the engine. On the air side, the flow from the compressor of the larger turbocharger is fed into the compressor of the smaller turbocharger. Schematic of ABB Turbocharging s Power2 two stage turbocharging system. An intercooler allows the second turbocharger to be more compact. 6

7 Power2 Control for variable Miller Two stage turbocharging control options. To adapt charge air output to demand from the engine under a full range of load and speed conditions, Power2 two stage turbocharging can be used with familiar turbocharger control options. Their control organs can be integrated into overriding electronic engine and powertrain management systems. Advanced control for Variable Miller Cycles The strong Miller Cycles which Power2 can enable assume an engine operating at its best point for power and/or fuel consumption and/or emissions, i.e. its maximum continuous rating or MCR. However, in many applications on land and sea, engines are expected to follow the load. At sea this is the case with both propulsion systems and generator sets feeding the onboard electrical consumers. On land variable load applications include: locomotive engines; travel and working functions on off-highway mobile equipment; diesel and gas engines driving compressor sets; generator sets feeding variable load consumers. VCM With its VCM Valve Control Management system, ABB Turbocharging can provide a method of adapting the Miller Cycle to lower loads via the stepless adjustment of inlet valve timing and lift. VCM is also capable of varying the output of the two turbochargers via its effect on the engine s gas exchange. The system achieves management of valve timing and lift by interposing a high pressure oil chamber into the engine valve train between the valve and its mechanical actuation system. A solenoid valve varies the filling of the chamber with engine lube oil pressurized by a camshaft actuated pump. The pump also feeds a brake unit above the valve to limit forces when the valve contacts its seat. At low loads or during start-up, longer inlet valve openings are needed than the short timings appropriate to strong Miller Cycles. They serve to avoid smoke emissions and poor transient response. Courtesy GE Jenbacher 7

8 ABB Turbocharging A unique partner for advanced engine components. Power2 two stage turbocharging is a major part of ABB Turbocharging s growing portfolio of products and services for engine builders and engine end users. They share the common theme of optimizing the performance, economy, reliability, availability, life cycle costs and not least the exhaust emissions of diesel and gas engines and hence ships, power plants, mobile equipment and locomotives fitted with ABB turbochargers. Proactive solutions For ABB Turbocharging this means proactively addressing the needs and concerns of both engine builders and engine end users to devise solutions which are both effective and economic. 8

9 Complementary technologies Power2 is one of two complementary building blocks ABB Turbocharging can offer engine builders as a unique partner to address what are presently their major concerns: Compliance with the strict limitations on emissions of oxides of nitrogen (NO x ) from engines on land and at sea due to be implemented in the middle of the present decade Increasing fuel efficiency in the face of the steady rise in the price of fossil fuels and international agreements governing emission of the greenhouse gas carbon dioxide (CO 2 ) Power2 and VCM interaction Meshing perfectly with Power2 two stage turbocharging is ABB Turbocharging s VCM Valve Control Management system for the progressive adjustment of valve timing and lift. These complementary technologies represent essential enablers of Variable Miller Cycles on large 4-stroke engines. On the one hand Power2 provides the high turbocharging pressure ratios needed for the very strong Miller Cycles required to realize high NO x reduction percentages. On the other hand VCM allows the engine s gas exchange to be optimized over a full range of engine operating conditions, hence allowing the effect of the Miller Cycle to be varied. Via its effect on engine gas exchange VCM is also an effective method of varying the output of the two turbochargers in the Power2 system. 9

10 Emissions compliance IMO Tier III and EPA Tier 4 are typical of the emissions legislation to be enacted in the middle of the present decade affecting engines with outputs over 500 kw. Courtesy Dresser Waukesha IMO Tier III The third stage of marine engine emissions legislation issued by the International Maritime Organisation and due in 2016 builds on IMO Tier II. In 2016 the generally applicable 20 % reduction in NO x emissions vis-à-vis IMO Tier I (introduced 2000) continues to govern NO x emissions on the high seas. However, IMO Tier III demands an 80 % reduction in NO x emissions from vessels operating in Emissions Control Areas, or ECAs. EPA Tier 4 standards Emissions standards issued by the USA s Environmental Protection Agency cover NO x emissions from water borne, mobile and stationary engines of all sizes used in a wide range of applications. Up to 2015, the EPA Tier 4 standard requires NO x emissions to be reduced by around 90 % compared to the 2008 Tier 1 baseline. IMO NO x curves ECAs are, broadly, coastal waters close to areas of population or environmentally sensitive locations. ECAs already designated are the complete East and West Coasts of the USA and Canada, straits like the English Channel, landlocked seas like the Baltic and numerous port approaches. 10 [g/kwh] NO x Tier I Tier II Tier III, from 1 January [1/min] Speed

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12 ABB Turbocharging Service network CHTUS EN 2012 ABB Turbo Systems Ltd, Baden/Switzerland Aalborg Aberdeen Adana Algeciras Antwerp Baden Bangkok Barcelona Bergen Bremerhaven Brisbane Buenos Aires Busan Cape Town Casablanca Cebu Chennai Chicago Chittagong Chongqing Colombo Copenhagen Dakar Dalian Dar es Salaam Davao Delhi Dortmund Douala Dubai Durban Fort de France Freeport Fukuoka Gdansk Genova Gothenburg Guangzhou Guatemala City Hakodate Hamburg Helsinki Hong Kong Houston Incheon Istanbul Izmir Jakarta Jeddah Kaohsiung Karachi Kobe Lahore Las Palmas Le Havre Lima Limassol Los Angeles Lunenburg Madrid Malta Manaus Manila Mannheim Marseille Melbourne Miami Montreal Mumbai Naples New Orleans New York Onomichi Oporto Oslo Panama Perth Piraeus Qingdao Quito Rijeka Rio de Janeiro Rotterdam Saint Nazaire Santo Domingo Santos Seattle Shanghai Singapore Southampton St. Petersburg Suez Sunderland Surabaya Sydney Talcahuano Tallinn Telford Tianjin Tokyo Vadodara Vancouver Varna Venice Vizag Vung Tau (Status: July 2012) ABB Turbo Systems Ltd Bruggerstrasse 71 a CH-5401 Baden/Switzerland Phone: Fax: turbocharging@ch.abb.com