GE NX JET ENGINE

Driving GE Ecomagination with the Low-Emission GEnx Jet Engine
July 20, 2005 -- EVENDALE, Ohio - With its GEnx jet engine, General Electric Company (GE) engineers are introducing breakthrough combustion technology that will dramatically reduce emissions in jet travel.

The GEnx engine is being developed for the new Airbus A350 and Boeing 787 aircraft. The GEnx enters airline service in 2008, and has already received more than $2 billion in orders on the strength of new technologies that make it the most fuel efficient, quiet, and low-emissions jet engine that GE has ever introduced for large jet aircraft.

The GEnx is part of GE's "ecomagination" products portfolio - GE's commitment to develop new, cost-effective technologies that will enhance customers' environmental and operating performance.

Lowering exhaust emissions in jet engines, especially oxides of nitrogen (NOx), will continue to be a worldwide requirement. With the GEnx, GE is at the forefront of that technology with a unique combustor called the Twin Annular, Pre-mixing Swirler (TAPS) combustor.

The combustor is the section of an engine where fuel is burned. GE has been maturing TAPS combustor technologies for almost a decade, and rig tests this year on the GEnx TAPS combustor have demonstrated very promising results. Here's how the TAPS combustor works:

The key to TAPS is how air and fuel are pre-mixed before they are burned in the combustor. Air from the high-pressure compressor is directed into the combustor through two high-energy swirlers adjacent to the fuel nozzles. This swirl creates a more homogeneous and leaner mix of fuel and air, which burns at lower temperatures than in previous jet engine designs.

The vast majority of NOx is formed by the reaction of oxygen and nitrogen at high temperatures; NOx levels are driven by the time that the burning fuel/air mixture stays at high temperatures.

The lower temperatures generated in the TAPS combustor results in significantly lower NOx levels. For example, at comparative thrust levels, GEnx NOx emissions will be more than 30 percent lower than the NOx emissisons of GE's highly popular CF6 engines powering commercial widebody aircraft today.

International jet engine emission standards will be lowered again in 2008. The GEnx emissions goal at entry into service is to be about 50 percent below the new established limits.

In addition to lowering ozone-depleting NOx emissions, GEnx's TAPS combustor will produce low levels of carbon monoxide, and unburned hydrocarbons. TAPS also has the potential to significantly reduce soot and related exhaust particulates. Also, because the TAPS combustor burns at lower temperatures, it will improve the life of components further downstream in the GEnx engine.

Although aircraft are only a minor source of the world's total level of NOx (EPA estimates aircraft at low-altitude operations created about seven-tenths of one percent of all NOx emissions in the USA) it is important to develop efficient and cost-effective, NOx-reduction technology for all sources.

The first full-engine testing of a TAPS combustor was completed on a CFM56-7B engine earlier this decade. The engine completed a grueling 4,000-cycle endurance test, after which the hardware remained in excellent condition. During component testing, the TAPS combustor demonstrated re-light capability at pressures equivalent to altitudes in excess of 30,000 feet. All of this experience was brought to the GEnx engine.

In February of this year, GE completed an extensive full-annular rig test with the GEnx TAPS combustor. It met all expectations in terms of emissions, efficiency, ignition, and durability. Using data from this test, the design has been further improved and will be validated in a second full-annular combustor test in the third quarter of 2005, paving the way for a full engine test in 2006.

Based on the architecture of the renowned GE90, the GEnx is the next-generation of engine technology to succeed GE's CF6, the best-selling engine for wide-body aircraft. Compared to the CF6 family, the GEnx will improve specific fuel consumption by 15 percent.

The GEnx is the world's only jet engine with a front fan case and fan blades made of composites for greater durability and weight reduction. It will operate with 18 fan blades (50 percent fewer than the CF6), which helps provide noise levels lower than any large commercial engine developed by GE.

HOW A JET ENGINE WORKS AMINATION

COMBINE CYCLE POWER GENERATION

SCALE JET ENGINES

Also known as miniature gas turbines or micro-jets.

Many model engineers relish the challenge of re-creating the grand engineering feats of today as tiny working models. Naturally, the idea of re-creating a powerful engine such as the jet, fascinated hobbyists since the very first full size engines were powered up by Hans von Ohain and Frank Whittle back in the 1930s.

Recreating machines such as engines to a different scale is not easy. Because of the square-cube law, the behaviour of many machines does not always scale up or down at the same rate as the machine's size (and often not even in a linear way), usually at best causing a dramatic loss of power or efficiency, and at worst causing them not to work at all. An automobile engine, for example, will not work if reproduced in the same shape at the size of a human hand.

With this in mind the pioneer of modern Micro-Jets, Kurt Schreckling, produced one of the world's first Micro-Turbines, the FD3/67. This engine can produce up to 22 newtons of thrust, and can be built by most mechanically minded people with basic engineering tools, such as a metal lathe. Its radial compressor, which is cold, is small and the hot axial turbine is large experiencing more centrifugal forces, meaning that this design is limited by Mach number. Guiding vanes are used to hold the starter, after the compressor impeller and before the turbine. No bypass within the engine is used.

RADIAL GAS TURBINES

1963, Norway, Jan Mowill initiated the development at Kongsberg Våpenfabrikk. Various successors have made good progress in the refinement of this mechanism. Owing to a configuration that keeps heat away from certain bearings the durability of the machine is improved while the radial turbine is well matched in speed requirement.

Concept
The difference between axial and radial turbines consists in the way the air flows through the components (compressor and turbine). Whereas for an axial turbine the rotor is 'impacted' by the air flow, for a radial turbine, the flow is smoothly orientated at 90 degrees by the compressor towards the combustion chamber and driving the turbine in the same way water drives a watermill. The result is less mechanical and thermal stress which enables a radial turbine to be more simple, more robust and more efficient (in a similar power range as axial turbines). When it comes to high power ranges (above 5 MW) the radial turbine is no longer competitive (heavy and expensive rotor) and the efficiency becomes similar to that of the axial turbines.

Advantages compared to axial turbines
Thanks to lower thermal and mechanical stress on the turbine tips, it is possible to boost power quite significantly by increasing the turbine entry temperature (increasing fuel input) which results in an improved mechanical efficiency. The lower mechanical stresses also enable radial turbines to handle single stage compression and expansion. As a result, the radial turbine does not need to be air cooled, which means that all the air entering the compressor is used only to drive the turbine which gives the radial design a strong advantage for cogeneration applications. Another result of avoiding air cooling is that power and efficiency are kept almost constant during the lifetime of the radial turbine whereas an axial gas turbine needs to be washed often to maintain ISO performance standards. The other advantage of such a simple rotor is that the bearings can be placed at the front, in the cold part, so less lubrication oil is needed, and there are no thermal losses due to lubrication of the hot parts of the rotor.

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MICRO TURBINES

Also known as:

*Turbo alternators
*MicroTurbine (registered trademark of Capstone Turbine Corporation)
*Turbo generator (registered trade name of Honeywell Power Systems, Inc.)

Micro Turbines are becoming widespread for distributed power and combined heat and power applications. They are one of the most promising technologies for powering hybrid electric vehicles. They range from hand held units producing less than a kilowatt, to commercial sized systems that produce tens or hundreds of kilowatts.


Part of their success is due to advances in electronics, which allows unattended operation and interfacing with the commercial power grid. Electronic power switching technology eliminates the need for the generator to be synchronized with the power grid. This allows the generator to be integrated with the turbine shaft, and to double as the starter motor.

Microturbine systems have many advantages over reciprocating engine generators, such as higher power density (with respect to footprint and weight), extremely low emissions and few, or just one, moving part. Those designed with foil bearings and air-cooling operate without oil, coolants or other hazardous materials. Microturbines also have the advantage of having the majority of their waste heat contained in their relatively high temperature exhaust, whereas the waste heat of recriprocating engines is split between its exhaust and cooling system. However, reciprocating engine generators are quicker to respond to changes in output power requirement and are usually slightly more efficient, although the efficiency of microturbines is increasing. Microturbines also lose more efficiency at low power levels than reciprocating engines.

They accept most commercial fuels, such as gasoline, natural gas, propane, diesel, and kerosene as well as renewable fuels such as E85, biodiesel and biogas.

Microturbine designs usually consist of a single stage radial compressor, a single stage radial turbine and a recuperator. Recuperators are difficult to design and manufacture because they operate under high pressure and temperature differentials. Exhaust heat can be used for water heating, space heating, drying processes or absorption chillers, which create cold for air conditioning from heat energy instead of electric energy.

Typical microturbine efficiencies are 25 to 35%. When in a combined heat and power cogeneration system, efficiencies of greater than 80% are commonly achieved.

MIT started its millimeter size turbine engine project in the middle of the 1990s when Professor of Aeronautics and Astronautics Alan H. Epstein considered the possibility of creating a personal turbine which will be able to meet all the demands of a modern person's electrical needs, just like a large turbine can meet the electricity demands of a small city. According to Professor Epstein current commercial Li-ion rechargeable batteries deliver about 120-150 Wh/kg. MIT's millimeter size turbine will deliver 500-700 Wh/kg in the near term, rising to 1200-1500 Wh/kg in the longer term

INDUSTRIAL GAS TURBINES

Industrial gas turbines differ from aeroderivatave in that the frames, bearings, and blading is of heavier construction. Industrial gas turbines range in size from truck-mounted mobile plants to enormous, complex systems. They can be particularly efficient——up to 60%——when waste heat from the gas turbine is recovered by a heat recovery steam generator to power a conventional steam turbine in a combined cycle configuration. They can also be run in a cogeneration configuration: the exhaust is used for space or water heating, or drives an absorption chiller for cooling or refrigeration. A cogeneration configuration can be over 90% efficient. The power turbines in the largest industrial gas turbines operate at 3,000 or 3,600 rpm to match the AC power grid frequency and to avoid the need for a reduction gearbox. Such engines require a dedicated enclosure, both to protect the engine from the elements and the operators from the noise.

Simple cycle gas turbines in the power industry require smaller capital investment than either coal or nuclear power plants and can be scaled to generate small or large amounts of power. Also, the actual construction process can take as little as several weeks to a few months, compared to years for base load power plants. Their other main advantage is the ability to be turned on and off within minutes, supplying power during peak demand. Because they are less efficient than combined cycle plants, they are usually used as peaking power plants, which operate anywhere from several hours per day to a couple dozen hours per year, depending on the electricity demand and the generating capacity of the region. In areas with a shortage of base load and load following power plant capacity, a gas turbine power plant may regularly operate during most hours of the day and even into the evening. A typical large simple cycle gas turbine may produce 100 to 300 megawatts of power and have 35–40% thermal efficiency. The most efficient turbines have reached 46% efficiency.

AUXILIARY POWER UNITS

Auxiliary power units (APUs) are small gas turbines designed for auxiliary power of larger machines, such as those inside an aircraft. They supply compressed air for aircraft ventilation (with an appropriate compressor design), start-up power for larger jet engines, and electrical and hydraulic power.

AMATEUR GAS TURBINES.

A popular hobby is to construct a gas turbine from an automotive turbocharger. A combustion chamber is fabricated and plumbed between the compressor and turbine. Like many technology based hobbies, they tend to give rise to manufacturing businesses over time. Several small companies manufacture small turbines and parts for the amateur.

AERODERIVATIVES AND JET ENGINES

Aeroderivatives and Jet Engines:
Airbreathing jet engines are gas turbines optimized to produce thrust from the exhaust gases, or from ducted fans connected to the gas turbines. Jet engines that produce thrust primarily from the direct impulse of exhaust gases are often called turbojets, whereas those that generate most of their thrust from the action of a ducted fan are often called turbofans or (rarely) fan-jets.
Gas turbines are also used in many liquid propellant rockets, the gas turbines are used to power a turbopump to permit the use of lightweight, low pressure tanks to be used, which saves considerable dry mass.
Aeroderivatives are also used in electical power generation due to their ability to startup, shut down, and handle load changes quicker than industrial machines. They are also used in the marine industry to reduce weight. The GE LM2500 and LM6000 are two common models of this type of machine.

OPERATIONAL THEORY OF GAS TURBINES

Gas turbines are described thermodynamically by the Brayton cycle, in which air is compressed isentropically, combustion occurs at constant pressure, and expansion over the turbine occurs isentropically back to the starting pressure.

In practice, friction, and turbulence cause:

non-isentropic compression: for a given overall pressure ratio, the compressor delivery temperature is higher than ideal.
non-isentropic expansion: although the turbine temperature drop necessary to drive the compressor is unaffected, the associated pressure ratio is greater, which decreases the expansion available to provide useful work.
pressure losses in the air intake, combustor and exhaust: reduces the expansion available to provide useful work.

Brayton cycleAs with all cyclic heat engines, higher combustion temperature means greater efficiency. The limiting factor is the ability of the steel, nickel, ceramic, or other materials that make up the engine to withstand heat and pressure. Considerable engineering goes into keeping the turbine parts cool. Most turbines also try to recover exhaust heat, which otherwise is wasted energy. Recuperators are heat exchangers that pass exhaust heat to the compressed air, prior to combustion. Combined cycle designs pass waste heat to steam turbine systems. And combined heat and power (co-generation) uses waste heat for hot water production.

Mechanically, gas turbines can be considerably less complex than internal combustion piston engines. Simple turbines might have one moving part: the shaft/compressor/turbine/alternative-rotor assembly (see image above), not counting the fuel system.

More sophisticated turbines (such as those found in modern jet engines) may have multiple shafts (spools), hundreds of turbine blades, movable stator blades, and a vast system of complex piping, combustors and heat exchangers.

As a general rule, the smaller the engine the higher the rotation rate of the shaft(s) needs to be to maintain tip speed. Turbine blade tip speed determines the maximum pressure that can be gained, independent of the size of the engine. Jet engines operate around 10,000 rpm and micro turbines around 100,000 rpm.

Thrust bearings and journal bearings are a critical part of design. Traditionally, they have been hydrodynamic oil bearings, or oil-cooled ball bearings. This is giving way to foil bearings, which have been successfully used in micro turbines and auxiliary power units.

SHORT AND BERIFE HISTORY OF GAS TURBINE

60: Hero's Engine (aeolipile) - apparently Hero's steam engine was taken to be no more than a toy, and thus its full potential not realized for centuries.
1500: The "Chimney Jack" was drawn by Leonardo da Vinci which was turning a roasting spit. Hot air from a fire rose through a series of fans which connect and turn the roasting spit.
1551: Taqi al-Din invented a steam turbine, which he used to power a self-rotating spit.[1]
1629: Jets of steam rotated a turbine that then rotated driven machinery allowed a stamping mill to be developed by Giovanni Branca.
1678: Ferdinand Verbeist built a model carriage relying on a steam jet for power.
1791: A patent was given to John Barber, an Englishman, for the first true gas turbine. His invention had most of the elements present in the modern day gas turbines. The turbine was designed to power a horseless carriage.
1872: The first true gas turbine engine was designed by Dr F. Stolze, but the engine never ran under its own power.
1894: Sir Charles Parsons patented the idea of propelling a ship with a steam turbine, and built a demonstration vessel (the Turbinia). This principle of propulsion is still of some use.
1895: Three 4-ton 100 kW Parsons radial flow generators were installed in Cambridge Power Station, and used to power the first electric street lighting scheme in the city.
1903: A Norwegian, Ægidius Elling, was able to build the first gas turbine that was able to produce more power than needed to run its own components, which was considered an achievement in a time when knowledge about aerodynamics was limited. Using rotary compressors and turbines it produced 11 hp (massive for those days). His work was later used by Sir Frank Whittle.
1913: Nikola Tesla patents the Tesla turbine based on the Boundary layer effect.
1914: Application for a gas turbine engine filed by Charles Curtis.
1918: One of the leading gas turbine manufacturers of today, General Electric, started their gas turbine division.
1920: The practical theory of gas flow through passages was developed into the more formal (and applicable to turbines) theory of gas flow past airfoils by Dr A. A. Griffith.
1930: Sir Frank Whittle patented the design for a gas turbine for jet propulsion. His work on gas propulsion relied on the work from all those who had previously worked in the same field and he has himself stated that his invention would be hard to achieve without the works of Ægidius Elling. The first successful use of his engine was in April 1937.
1934: Raúl Pateras de Pescara patented the free-piston engine as a gas generator for gas turbines.
1936: Hans von Ohain and Max Hahn in Germany developed their own patented engine design at the same time that Sir Frank Whittle was developing his design in England.

GAS TURBINE

A gas turbine, also called a combustion turbine, is a rotary engine that extracts energy from a flow of combustion gas. It has an upstream compressor coupled to a downstream turbine, and a combustion chamber in-between. (Gas turbine may also refer to just the turbine element.)
Energy is added to the gas stream in the combustor, where air is mixed with fuel and ignited. Combustion increases the temperature, velocity and volume of the gas flow. This is directed through a (nozzle) over the turbine's blades, spinning the turbine and powering the compressor.
Energy is extracted in the form of shaft power, compressed air and thrust, in any combination, and used to power aircraft, trains, ships, generators, and even tanks.

ALIGNMENT (EXPLAINATION)

Alignment is the adjustment of an object in relation with other objects, or a static orientation of some object or set of objects in relation to others.

* An alignment of megaliths: see stone row.
* An alignment (archaeology) in archaeology is a secondary or circumstantial form of evidence used to associate features such as postholes
* Alignment (role-playing games) refers to the moral and ethical perspective of the player characters, non-player characters, monsters, and societies in the game.

* This meaning applies in particular to alignment in the Dungeons & Dragons role-playing game.

It has a more specific meaning in some disciplines:

* Business/IT alignment, Business/IT alignment optimizes the relational mechanisms between the business and IT organization by working on the IT effectiveness of the organization in order to maximise the business value from IT.
* Typographic alignment, in typesetting, lines of text or images can be aligned left, right, centered or justified.
* Sequence alignment shows similarities between protein or nucleic acid sequences (also in bioinformatics).
* Structural alignment presents similarities in 3D structure of protein molecules.
* Strategic alignment refers to business structure and information technology fit in relation to business strategy and external environment. When alignment is attained firm gains competitive advantage and increase performance. Strategic information systems belong in this category.
* Wheel alignment in an automobile means adjustment of the camber, castor, and/or toe to improve performance and maintain proper tire wear characteristics of the car
* Data structure alignment, in computer programming, refers to arranging data in memory
* Parallel text alignment, in artificial intelligence
* Ontology alignment, in heterogeneous knowledge bases, the expression of the correspondences between two ontologies is called ontology alignment
* Body alignment, in sport and dance, the proper placement of the bones so that the muscles do less work

[1]

* Morphosyntactic alignment, in linguistics, the properties determining the grammatical relationship between verbal arguments of various kinds
* Fibre alignment, in optoelectronics, to connect two Optical fibers to each other
* Shaft alignment, in mechanical engineering, to adjust two coupled rotating machines
* Planetary alignment, another term for Syzygy in astronomy

Other fields where the term "alignment" has a particular meaning:

* Ley line, an interpretation of an alignment of a number of places of geographical interest, such as ancient megaliths.
* In integrated circuit fabrication, alignment is the step in a photolithographic process in which a mask used to pattern a layer of the circuit is registered in its x-y position with respect to the wafer (usually silicon) on which the circuit is being formed.

LASER ALIGNMENT

When two machines are connected together through a shaft coupling, every effort must be made to eliminate misalignment of those shafts which can lead to damage or wasteful loss of energy. Lasers are highly accurate and easy to use in aligning objects. Using laser shaft alignment techniques can reduce the amount of time in the alignment process.
Precise laser coupling alignment is used to reduce bearing and seal damage, minimize energy loss, and reduce production downtime. Performing coupling alignment on a scheduled basis will make machinery last longer and perform more efficiently.
There are several methods used to align couplings including 'eyeing' it, dial calibration and laser alignment. Each method varies in its degree of accuracy and dial calibration can be a very time consuming process.
Utilizing a state-of-the-art laser measurement system, a technician will measure and align couplings, universal joints and belts. This alignment allows conveyor systems and manufacturing machines to run in a straight line. A factory line that makes masking tape is a good example of the need for precision alignment. In order for the tape to spool neatly and at a high rate of speed, the take up reel shaft must be exactly perpendicular to the incoming tape. Any deviation will decrease the quality of the end product.
To control the co-linearity and angle of two shafts at the coupling, where the power is transmitted - laser shaft alignment technology can help to perform the measurement easily. The Laser "shoots" onto a position sensitive detector, during continuously rotating the shafts the detector collects all changes and can calculate the gap & offset at the coupling position.
In addition the shaft alignment device can check whether the alignment is in within OEM tolerances or not.

LASER ALIGNMENT TOOLS

F CLASS GAS TURBINES

Maximum Reliability
With millions of hours of operation, F class turbines have established GE as the clear industry leader for successful fired hours in advanced technology gas turbines. Representing the world's largest, most experienced fleet of highly efficient gas turbines, designed for maximum reliability and efficiency with low life cycle costs, GE's F class turbines are favored by both power generators and industrial cogenerators requiring large blocks of reliable power.
Introduced in 1987, GE's F class gas turbines resulted from a multi-year development program using technology advanced by GE Aircraft Engines and GE's Global Research Center. GE continually advances this technology by incrementally improving the F class product to attain ever higher combined cycle efficiencies.
GE's F class gas turbines offer flexibility in cycle configuration, fuel selection and site adaptation. All F class gas turbines include an 18-stage axial compressor and a three-stage turbine, and feature a cold-end drive and axial exhaust, which is beneficial for combined cycle arrangements where net efficiencies over 58 percent can be achieved
The available models of F Class are,
MS 9001 FA
MS 7001 FA
7FB
9FB

Maximum Reliability
From Argentina to Singapore, world power producers require reliable power generation. The 9FA is the 50 Hz gas turbine choice for large combined cycle applications.
Since the 9FA is an aerodynamic scale of the highly successful 7FA gas turbine, it too has experienced industry-leading reliability. Key advantages of the MS9001FA (9FA) gas turbine include its fuel-flexible combustion system and higher output performance.
The 9FA gas turbine is configured with the robust Dry Low NOx (DLN) 2.0+ combustor, which is ideally suited for the diverse fuels typical of the worldwide 50 Hz power generation market. The DLN 2.0+ combustor is the industry leader in pollution prevention for 50 Hz combined cycle applications, with greater than 56 percent efficiency and achieving less than 25 ppm NOx.
The 9FA is a building block that can be configured to meet site and power requirements. For re-powering applications where space limitation is a key consideration, the 9FA gas turbine can be configured in a single-shaft combined cycle arrangement with the generator and steam turbine. For large combined cycle or cogeneration power plants where flexible operation and maximum performance are the prime considerations, the 9FA can be arranged in a multi-shaft configuration where one or two gas turbines are combined with a single steam turbine to produce power blocks of 390 or 780 MW.
Simple Cycle Performance 50Hz
Output 255.6 MW
Heat Rate 9250 Btu/kWh (9757 kJ/kWh)
Pressure Ratio 17.0:1
Mass Flow 1,413 lb/sec (641 kg/sec)
Turbine Speed 3000 rpm
Exhaust Temperature 1,116°F (602°C)
Model Designation PG9351FA
Combined Cycle Performance 50Hz (S109FA) 50Hz (S209FA)
Net Plant Output 390.8 MW 786.9 MW
Heat Rate 6020 Btu/kWh (6350 kJ/kWh) 5980 Btu/kWh (6305 kJ/kWh)
Net Plant Efficiency 56.7% 57.1%
GT Number & Type 1 x MS9001FA 2 x MS9001FA

GE WORLD LEADER IN BREAKTHROUGH TECHNOLOGY

GE offers the widest range of heavy duty gas turbines available, ranging from 26 to 480 megawatts. Within the GE product line are machines for every utility, IPP and industrial application, from pure power generation to cogeneration and district heating.
Our worldwide installed fleet totals more than 6,000 gas turbines, the largest installed base of any gas turbine supplier. These units have accumulated well over 200 million fired hours of operating experience at unparalleled reliability levels. Always on the cutting edge of gas turbine technology, GE offers a wide array of technological options to meet the most challenging energy requirements. Using an integrated approach that includes parts, service, repair and project management, we deliver results that contribute to our customers' success.