Post on 04-Apr-2018
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MICROTURBINE GENERATOR SYSTEM
Presented by
N.MAHESH09261A0240
E.E.E , B.TECH
MGIT,GANDIPET
MOBILE NO:7416380626
naallamahesh10@gmail.com
P.R.S.C .Dheekshith
09261A0245
E.E.E ,B.TECH
MGIT,GANDIPET
MOBILE NO:9032726857
dp50657@gmail.com
mailto:naallamahesh10@gmail.commailto:dp50657@gmail.commailto:naallamahesh10@gmail.commailto:dp50657@gmail.com7/30/2019 Micro Turbine Generating System
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ABSTRACT:
The Turbine Generating Systems
presents us a idea of generating stations using vast
land and human resources to produce power
.Generally turbines occupies a large area and a
specified location ,and it requires large
infrastructure. The main disadvantage of Turbine
generating system is that it cannot be located in a
highly populated area. Many of the disadvantages
of Turbine generating systems can be resolved in
MICROTURBINE GENERATING SYSTEM.
MICROTURBINES are
becoming wide spread for distributed power and
combined heat and power applications. They
range from handheld units producing less than a
kilowatt to commercial sized systems that produce
tens or hundreds of kilowatts. They are also known
as "turbo alternators", or "gensets".They evolved
from automotive and truck turbochargers,
auxiliary power units for airplanes, and small jet
engines and are comprised of a compressor,
combustor, turbine, alternator, recuperator, and arefrigerator. The engine itself is about the size of a
beer keg . Microturbine systems have many
advantages over piston engine generators, such as
higher power density (with respect to footprint and
weight), extremely low emissions and few, or just
one, moving part. They accept most commercial
fuels, such as natural gas, propane, diesel and
kerosene. They are also able to produce renewable
energy when fueled with biogas from landfills and
sewage treatment plants. Microturbine designs
usually consist of a single stage radial
compressor, a single stage radial turbine and a
recuperator .Typical micro turbine efficiencies are
25 to 35 percent. When in a combined heat and
power cogeneration system, efficiencies of greater
than 80 percent are commonly achieved.
Microturbines are the systems which can belocated even in a small location.
Part of their success is due to
advances in electronics, which allow 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,
for example, the generator to be integrated with
the turbine shaft, and to double as the startermotor. Microturbine generating systems found
their applications in Co-generation , Distributed
power generation,Backup generators , Indoor pool
, Hybrid vehicles etc.
INTRODUCTION:
Microturbines are the new
type of combustion turbines being used for
stationary energy generation applications. They are
small combustion turbines, approximately the size
of a refrigerator, with outputs of 25kw to 500kw,
and can be located on sites with space limitation
for power production. Microturbines are composed
of a compressor, combustor, turbine, alternator,
recuperator, and generator. Waste heat recovery
can be used in combined heat and power system to
achieve energy efficiency levels greater than 80%.
In addition to power generation micro turbines
offer an efficient and clean solution to directmechanical drive markets such as compression and
air conditioning. Microturbines have installed with
considerable success in office and apartment
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building, hotels and motels. Supermarkets, school
and college, office and industrial parks, small
industries, and numerous other facilities both in the
US and abroard.They provide not only electricity,
but the thermal energy to provide for all heating
and cooling needs.
WHAT IS MICROTURBINE ?
Microturbinesare small combustion turbines
approximately the size of a refrigerator with
outputs of 25kw to 500kw. They evolved from
automotive and truck turbochargers, auxiliary
power units for airplanes, and small jet engines and
are comprised of a compressor, combustor, turbine,
alternator, recuperator, and a refrigerator. The
engine itself is about the size of a beer keg. Themost popular models have just one moving parts
a shaft with a turbine wheel on one end , a
permanent magnet generator on other end, and an
air compressor wheel in the middle. This assembly
rotates at up to 96,000 rpm. At that speed,
traditional oil-lubricated bearings are severely
challenged. Accordingly the most popular micro
turbine engines use air bearing to float the shaft.
Not only the turbine turning at highrpm, so is the generator. The generator in turn
produces a high frequency electrical output, which
is then converted by power electronics unit to grid
compatible 400-to-480-volts alternating current,
10-to-60 hertz.3phase power.
Microturbine offer a number of
potential advantages compared to other
technologies for small-scale power generation.
These advantages include a small number ofmoving parts, compact size, light-weight, greater
efficiency, lower emission, lower electricity cost,
and opportunities to utilize waste fuels. They have
the potential to be located on sites with space
limitation for the production of power. Waste heat
recovery can be used with these systems to achieve
efficiencies greater than 80%.
There is very definitely a trend
toward installing microturbine system onsitenotonly for generating electric power. But also for
meeting site heating and cooling needs. Such
microturbine configuration are called combined
heat and power, or combined cooling, heat and
power system. The core idea is this: when burning
a fuel in a micro turbine unit, dont just use the
resulting heated gases to spin a turbine and
generate electricity. There is still a huge amount of
thermal energy in the turbine exhaust. Dont waste
that valuable energy to the atmospherewhich is
what they do in most central power plants .
Instead, use a heat exchanger to
capture much of that thermal energy and use it to
meet all the heating and cooling needs of the site.
When a microturbine unit is arranged in combined
heat and power(CHP) mode, heat from the turbine
stack is captured and used to meet some or all the
heating and cooling needs of the facility. This
makes for much more efficient fuel use. Instead of
just using 35% of thermal energy released during
fuel combustion , with CHP one would be using
65% or more of the fuels thermal energy.
The 30-kilowatt model of
Microturbine is very versatile, being able to burn
several gaseous or liquid fuelsnatural gas,
propane, biogas, diesel, and kerosene.
Microturbine Overview
Commercial Available - Yes (limited)
Size Range - 25-500 kW
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Fuel - Natural gas,
hydrogen, propane, and diesel.
Efficiency - 20-30%
(recuperated)
Environmental - low (
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turning on the single turbo-compressor shaft or
with a separate power turbine driving a gearbox
and conventional 3,600 rpm generator. The high-
speed generator of the single-shaft design employs
permanent magnet alternator, and requires that the
high frequency output (about 1,600 Hz for a 30 kW
machine) be converted to 60 Hz for general use.
This power conditioning involves rectifying the
high frequency AC to DC, and then inverting the
DC to 60 Hz AC. Power conversion comes with an
efficiency penalty (approximately five percent).To
start-up a single shaft design, the generator acts as
a motor turning the turbo-compressor shaft until
sufficient rpm is reached to start the combustor.
Full start-up requires several minutes. If the system
is operating independent of the grid (blackstarting), a power storage unit (typically battery
UPS) is used to power the generator for start-up.
RECUPERATOR:-
Recuperators are heat exchangers
that use the hot turbine exhaust gas (typically
around 1,200F)to preheat the compressed air
(typically around 300F) going into the combustor,
thereby reducing the fuel needed to heat the
compressed air to turbine inlet temperature.Depending onmicroturbine operating parameters,
recuperators can more than double machine
efficiency. However, since there is increased
pressure drop in both the compressed air and
turbine exhaust sides of the recuperator, power
output typically declines 10 to 15% from that
attainable without the recuperator. Recuperators
also lower the temperature of the micro turbine
exhaust, reducing the micro turbines effectiveness
in CHP applications.
BEARINGS:
Microturbines operate on either oil-
lubricated or air bearings, which support the
shaft(s). Oil lubricated bearings are mechanical
bearings and come in three main forms high-
speed metal roller, floating sleeve, and ceramic
surface. The latter typically offer the most
attractive benefits in terms of life, operating
temperature, and lubricant flow. While they are a
well-established technology, they require an oil
pump, oil filtering system, and liquid cooling that
add tomicroturbine cost and maintenance. In
addition, the exhaust from machines featuring oil
lubricated bearings may not be useable for direct
space heating in cogeneration configurations due to
the potential for contamination. Since the oil nevercomes in direct contact with hot combustion
products, as is the case in small reciprocating
engines, it is believed that there liability of such a
lubrication system is more typical of ship
propulsion diesel systems (which have separate
bearings and cylinder lubrication systems) and
automotive transmissions than cylinder lubrication
in automotive engines.. Air bearingshave been in
service on airplane cabin cooling systems for many
years. They allow the turbine to spin on a thin layerof air, so friction is low and rpm is high. No oil or
oil pump is needed. Air bearings offer simplicity of
operation without the cost, reliability concerns,
maintenance requirements, or power drain of an
oil supply and filtering system. Concern does exist
for the reliability of air bearings under numerous
and repeated starts due to metal on metal friction
during startup, shutdown, and load changes.
Reliability depends largely on individual
manufacturers' quality control methodology more
than on design engineering, and will only be
proven after significant experience with substantial
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numbers of units with long numbers of operating
hours and on/off cycles.
POWER ELECTRONICS:-
As discussed,
single-shaft micro turbines feature digital power
controllers to convert the high frequency AC
power produced by the generator into usable
electricity. The high frequency AC is rectified to
DC, inverted back to 60 or 50 Hz AC, and then
filtered to reduce harmonic distortion. This is a
critical component in the single-shaft microturbine
design and represents significant design
challenges, specifically in matching turbine output
to the required load. To allow for transients and
voltage spikes, power electronics designs are
generally able to handle seven times the nominal
voltage. Most microturbine power electronics are
generating three phase electricity. Electronic
components also direct all of the operating and
startup functions. Microturbines are generally
equipped with controls that allow the unit to be
operated in parallel or independent of The grid,
and internally incorporate many of the grid and
system protection features required for
interconnect. The controls also allow for remotemonitoring and operation.
HOW MICROTURBINE WORKS?
Microturbine engine has only one
moving part, basically a shaft. At one end of that
shaft is a turbine wheel; at the opposite end of the
shaft is a permanent magnet electric generator; and
positioned at the mid point of that shaft is an air
impeller wheel (ie; an air compressor) for drawing
ambient air , compressing it , then pumping it into
combustor. Fuel is then injected into the
combustor, where it then mixes with compressed
air. Combustion occurs and the resulting gasses
expand and rush out through the turbine, spinning
it to a very high rpm.
This whole microturbine system is packaged in an
enclosure not much bigger than a refrigerator
about 7 feet tall, 2.5 feet wide and 6.5 feet deep.
Ambient air is first drawn into the microturbine
system enclosure, filtered, then passed over theelectric generator, which is kept cool by this
passing air. Next, the air is drawn into the impeller
(or compressor), which compresses the air before
pumping it into the combustor
SCHEMATIC DIAGRAM OF
RECUPERATED TYPE MICROTURBINE
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Now, a part of that compressed air stream exiting
the impeller (compressor) is diverted to the air
bearing. The microturbine shaft in effect now rides
on a thin film of compressed airthis being in the
thin annular space between the rotating shaft and
the stationary bearing housing
TYPES OF MICROTURBINE
Microturbine are classified
by the physical arrangement of the component
parts; single Shaft, simple cycle, or recuperated,
inter-cooled, and reheat. The machines generally
rotate over 40000 revolutions per minute. The
bearing selection oil or air is dependent on
usage .A single shaft microturbine with high
rotating speeds of 90000 to 120,000 revolutionsper minute is the more common design ,as it is
simpler and less expensive to built. Conversely, the
spilt shaft is necessary for machine drive
applications, which does not require an inverter to
change the frequency of the AC power.
Microturbine generator can also be divided into
two general classes:
Unrecuperated (simple cycle) micro
turbinein a simple cycle, or
unrecuperated, turbine, Compressed air is
mixed with fuel and burned under constant
pressure condition. The resulting hot gas is
allowed to expand through a turbine to
perform work. Simple cycle microturbines
3have lower efficiencies at around 15%, but
also lower capital costs, higher reliability,
and more heat available for cogeneration
application than recuperated unit.
Recuperated
microturbinesrecuperated units use a sheet
metal heat exchanger that recovers some of the
heat from an exhaust stream and transfers it to the
combustor. Further exhaust heat recovery can be
used in a cogeneration configuration. The figures
below illustrate a recuperated microturbine system.
The fuel-energy-to electrical-conversionefficiencies are in the range of 20 to 30%. In
addition, recuperated units can produce 30 to 40%
fuel savings from preheating.
Recuperated Microturbine
CHARACTERITICS OF
MICROTURBINES:
Some of primary applications for microturbineinclude:
GeneratorCoolingFins
CombustionChamb
er
ExhaustOutlet
Recuperator
AirBearing
s
Compressor
Generator
Turbine
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Distributed generationstand alone, on
site applications remote from power grids.
Quality power and reliabilityreduced
frequency variation, voltage transients,
surges, dips, or other disruptions.
Stand by powerused in the event of an
outage, as back up to electric grid.
Peak shavingthe use of microturbines
during times when electric use and demand
charges are high.
Boost powerboost localized generation
capacity and on more remote grids.
Low cost energythe use of microturbines
as base load primary power that is less
expensive to produce locally than it is to
produce from the electric utility Combined heat and power (cogeneration )
increase the efficiency of on-site power
generation by using the waste heat for
existing thermal process.
Advantages of Distributed Generation:
As energy need not be
transmitted there is no need of any largetransmission infrastructure. Thus the losses during
power transmission are greatly reduced. The
combined heat and power (CHP) technology can
be applied to micro turbines to increase its
efficiency. This lowers emission and operating cost
by reducing losses and increasing efficiency. From
a companys point of view, it gives greater control,
choice and flexibility in meeting needs for power
and heat energy.
Selected strength and weaknesses of
microturbine technology are:
Strengths
Small number of moving parts
Compact size
Lightweight
Good efficiencies in cogeneration
Low emission Can utilize waste fuels
Long maintenance interval
No vibration
Less noise than reciprocating engines
Weaknesses
Low fuel to electricity efficiencies
Loss of power output and efficiency with
higher ambient temperature and elevation.
APPLICATIONS OF MICROTURBINES
Microturbines
are being increasingly preferred over reciprocating
engines in many applications. These include:
Combined heat and power (co-generation)
Waste heat from the micro turbine
can be transferred via a heat exchanger to produce
steam or provide hot water for local area. The hot
water can be used in a green house to grow plants;
water can duct to provide central heating in
building in winter. Thermal hosts can found easier
because the the produced by each microturbine unit
is so much that by a large power station.
Distributed power generation:
Electricity isgenerated locally to meet demand in the local area,
for example a small towns electricity supply. This
can relieve congestion of the distribution network
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or power grid. Hospitals, hotels, factories and
holiday resorts can install distributed power at
remote sites without grid access.
Distributed generation provides a
wide range of services to consumers and utilities,
including standby generation, peak shavingcapability, base load generation and co-generation.
Hospitals
The waste heat from the generator
can be used to create for the sterilization of
medical equipment as well as for laundry purposes,
like the daily changing of bed linen. It can also act
as backup power supply, which is critical for the
smooth functioning of various life-supporting
equipments.
Backup generators
Microturbines can also be used in remote areas
where there is no access to electricity. It could
provide electricity for research station in the
middle of a jungle or desert, where there is no
ready access to diesel supplies but is located near
gaswells.
Indoor pool
The indoor pool, which
contains 200,000 gallons of water and a dive pool
containing 250,000 gallons of water. Before the
DG installation, all heat was provided by steam
purchased from the CU Power House, located on
campus. A large heat exchanger is in place below
ground on the west side of the building.
Temperature sensors monitored the pool water and
steam was metered in as needed to maintain the
desired temperature. The pools are used year round
and need to be maintained at a temperature of
about 81 F.
Tabrizi cited several factors that made
this microturbine a desirable choice for installation
at the Recreation Center pool. These include the
small footprint, high efficiency, combined heat and
power availability, the ability to locate the unit
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close to the point of use and the clean emissions.
Vehicle applications
Hybrid vehicle( microturbine to high speedalternator)
In hybrid
vehicle applications, the power produced by a
microturbine is converted into electricity by a high
speed alternator. The power is used to drive
electric motors connected to the wheels. Any
excess energy is directed to an energy storage
system such as batteries or flywheels. The
operating mode of the hybrid approaches ranges
from battery-primary systems where the
microturbine can be a battery charger, to engine-
primary system where the batteries help the micro
turbine meet peak power needs, e.g. during
acceleration.
Hybrid vehicle (microturbine and fuel cell
together)
A hybrid
combination of micro turbines with fuel cellscan increase overall system efficiencies.
Hybrid systems take advantage of an increase
in fuel cell efficiency with an increase in
operating pressure. The microturbine
compressor stage is used to provide this
pressure. The fuel cell produces heat along
with power, and this heat energy is used to
drive the microturbines turbine stage. If the
fuel cell produces enough heat the micro
turbine can generate additional power. For
the hybrid combination, efficiency is expected
to be as much as 60% and emission less than
1.0 ppm NOx, with negligible SOx and other
application.
ECONOMICS OF MICROTURBINES
Microturbin
e capital costs ranges from $700 -$1,100\kW.
These costs include all hardware, associatedmanuals, software, and initial training.
Adding heat recovery
increases the cost by $75-$350\kW. Installation
costs very significantly by location but generally
add 30-50%to the total installed cost.Microturbine
manufacturers are targeting a future cost below
$650\kW. This appears to be feasible if the market
expands and sales volumes increase.With fewer
moving parts, microturbine vendors hope the unitscan provide higher reliability than conventional
reciprocating generating technologies.
Manufacturers expect that initial units will require
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more unexpected visits, but as the products mature,
once-a- year maintenance schedule should suffice.
Most manufacturers are targeting maintenance
intervals of 5,000-8,000 hours.
Maintenance costs for micro turbine
units are still based on forecasts with minimal real-life situation. Estimates range from $0.005-$0.016
per kWh, which would be comparable to that for
small reciprocating engine systems.
MICROTURBINE COST
Capital cost $700-$1100\Kw
O&M Cost $0.005-0.016\kw
Maintenance Interval 5,000-8,000hrs
ADVANCED MICROTURBINE PROGRAM
The Advanced Microturbine
Program is a six-year program for FY 2000-2006
with a Government is investment of over $60
Million. End-use applications for the program are
open and include stationary power applications in
industrial, commercial, and institutional sectors.
The program includes competitive solicitation (s)
for engine conceptual design, and sensors and
controls. Technology evaluations and
demonstrations are also part of the
program.Planned activities for this program focus
on the following performance targets for the next
generation of ultra-lean, high efficiency
microturbine product design:
High efficiency: Fuel- electricity
conversion efficiency of at least 40%.
Environment : NOx< 7ppm (natural gas)
Durability: 11,000 hrs of reliable operation
between major overhauls and a service life
of at least 45,000 hrs.
Cost of power: System costs< $500/kW,
costs of electricity that are competitive with
the alternatives (including grid) for market
applications.
Fuel flexibility: Options for using for using
multiple fuels including diesel, ethanol,
landfill gas, and bio-fuels.
MICROTURBINE MANUFACTURERS
The leading microturbine manufacturers are
1. Bowman power systems
2. Capstone Turbine Cooperation
3. Elliott energy systems
4. Turbec AB
5. Ingersoll-Rand Company
CONCLUSION
Micro-turbines and miniature
thermal devices pose unique challenges and
opportunities for combustion in small volume. The
principal difficulties are associated with limited
residual time and heat transfer losses due to high
surface to volume ratio. This paper addresses a
preliminary analysis of Micro-turbine .The micro-
turbine is in early stages of pre-production and is
still in the developmental phase .The coupling of
micro-turbine with a high temperature fuel cell
(SOFC solid oxide fuel cell) is one of them .If
the waste heat is used the overall fuel utilization
efficiency can be increased. Major features,
parameters and performance of the micro-turbine
are discussed here. Fully understanding these andidentifying the solutions, it is key to the future
establishing of an optimum overall system. In the
case of the micro-turbine changes will be minor as
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they enter production on a large scale within the
next year or so, there is an extensive efforts are
expanded to reduce unit cost .It is reasonable to
project that a high performance and cost effective
hybrid plant, with high reliability, will be ready for
commercial service in the middle of the first
decade of the twenty century.