lecture gasifier

8/6/2019 Lecture Gasifier

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Highlights

What is IGCC? Why IGCC? Historical Aspects Working Principle Advantages of IGCC

IGCC in NTPC perspective Barriers to Deployment Conclusion


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Why IGCC ?

CONVENTIONAL COAL PLANTS :

Future challenges :Comparatively lower efficiency & Higher

emissionsKyoto Protocol Norms & Strict norms of loanpolicyLimited Coal Stock & Other options areexpensive

Land cost & Ash disposal


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Why IGCC ?NON CONVENTIONAL: Future

challenges : Low capacity Low efficiency High capital cost Less flexibility

Lesser reliabilityTo address these challenges, new coal utilization technologies are being developed. One of the more

promising of these is Integrated Gasification Combined Cycle (IGCC)

power generation


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In the 1970s , interest in coal gasification revived because of increasing cost and less availability of

natural gas. Coal gasification, however, likely found its most

important market application in the 1980s and 90s .Driven primarily by environmental concerns over thetraditional burning of coal, gasification emerged as anextremely clean way to generate electric power.

By turning coal into a combustible gas that could becleansed of virtually all of its pollutant-formingimpurities and burned in a gas turbine, coal couldrival natural gas in terms of environmental

performance.

Historical Aspects


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How does IGCC work?

IGCC is a combination of two leadingtechnologies.

The first technology is called coalgasification , which uses coal to create aclean-burning gas (syngas).

The second technology is called combined-cycle , which is the most efficient method of

producing electricity commercially availabletoday


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End-productseeds Gas RefiningasificationIGCC Sc hem at ic

Coal

Biomass

PetroleumCoke/Resid.

Waste

FEEDSTOCK

MarketableSolid

Byproducts

GASIFIER

OXYGEN

STEAM

ASU

H2

STACK

FUELCELL

H2

ELECTRICPOWER

TRANSPORTATIONFUEL

STEAM

SULFUR/SULFURIC ACID

FUELCHEMICALS

PARTICULATES

SYNGAS

C C

CO 2

ELECTRICPOWER

ELECTRICPOWER

AIR COMP. + GT G

G

HRSG

STEAMTURBINE

WATER

CombinedCycle


FUELCHEMICALS

PARTICULATES

SYNGAS


FUELCHEMICALS

PARTICULATES

SYNGAS


FUELCHEMICALS

PARTICULATES

SYNGAS


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Advantages of IGCC Higher Efficiency Lower Emission Comparable Cost Multiple Fuel Options

Marketable Byproducts Lesser Area Requirement

Higher Output Less Solid Waste and Water Use


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Higher Efficiency As we have already discussed, currently IGCC efficiency

approaching 50%, With development of new gas turbine

concepts and increased process temperatures, efficienciesof more than60% can be achieved. Future concepts that incorporate afuel cellor fuel cell-gas

turbine hybrid could achieve evenhigher efficiencies. If any of the remaining waste heat can be channeled into

process steam or heat, perhaps for nearby factories ordistrict heating plants, the overall fuel use efficiency ofuture gasification plants could reach70 to 80percent.

Higher efficiencies translate into moreeconomical electricpower and potential savings for ratepayers. A moreefficient plant also usesless fuel to generate power.

Advantages of IGCC


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Plant efficiency can be improved furtherby:

1. Injecting the nitrogen from the airseparation unit into the fuel gas priorto the gas turbine

2. Utilizing air from the gasturbine/compressor in the airseparation unit.

Higher Efficiency (contd)


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Lower Emission

High SO 2 removal (e.g., 99 % or higher)and low-NO

Xemissions (below 50 ppm )

are achieved.

The emissions of particulates, NOx andSO 2 from IGCC units meet all currentstandards .

On most units, sulphur is produced inelemental form as a by-product .

Advantages of IGCC

SO X & NO X EMISSION


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Lower Emission

Advantages of IGCC

Carbon dioxide

Up to 100% of Carbon dioxide can be captured fromthe coal syngas (carbon monoxide and hydrogen)through a water/gas shift process

Carbon capture at IGCC plants is significantly easierand much more economic than at conventionalpulverized coal plants and more economic on a $/tonbasis than at natural gas plants

Even without carbon capture and sequestration,IGCC plants are more efficient than conventional coalplants and emit less CO 2.


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The environmental benefits stem from the capability to cleanseas much as 99 percent of the pollutant-forming impurities fromcoal-derived gases.

Sulfur in coal, can be extracted in either a liquid or solid formthat can be sold commercially.

In an IGCC plant, the syngas produced is virtually free of fuel-bound nitrogen. NOx from the gas turbine is, therefore,limited to thermal NOx. Diluting the syngas allows for NOx

emissions as low as 15 parts per million. Thus avoids acidraining.

Multi-contaminant control processes are being developed thatreduce pollutants to parts-per-billion levels and are effective incleaning mercury and other trace metals in addition to othe rimpurities.

Advantages of IGCC

Envi ronm en t a l Benef i t s


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Comparable Cost IGCC cost projections range from US$1200 to

1400/kW; 10 to 30 percent higher than for pulverized-coal with wet scrubbers.

US Department of Energy (DOE) forecasts that by the year 2010, the operating cost of IGCC based electricity power generation could be inthe order of 3.7/kWh ( 1.5Rs/kWh ), which ischeaper than advanced coal fired power plantand also comparable to natural gas firedcombined cycle units

A capital cost of around 1000$/kW ( 4.3CroreRs/kW is also achievable.

Advantages of IGCC


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IGCC Plant Capital Cost Trends

Comparable Cost

0

2

4

6

8

10

12

14

16

1975 1980 1985 1990 1995 2000 2005 2010 year

C r o r e R s p e r

M W

Advantages of IGCC


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Multiple Fuel Options

COAL

BIO MASS

PETROLEUM/COKE RESIDUE

WASTE

Advantages of IGCC


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Marketable Byproducts

The gasification process in IGCC enablesthe production of not only electricity, buta range of chemicals, by-products for industrial use, and transport fuels, e.g.; Hydrogen

Ammonia Methanol Sulphur Slag

Advantages of IGCC

FUEL

CHEMICALS


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Pathway to : Hydrogen Economy Research and development in recent years has focused onhydrogen fuel cells which hold great promise as low-

pollution automobile engines if certain difficulties can beovercome. Water, the only waste product of a hydrogen-oxygen fuel cell, is non-polluting and can be used to cool theengine. The oxygen the cells need is readily available in air.

Hydrogen, however, is not so readily available, and there isno existing delivery system to convey hydrogen to all theplaces people would need it to power their cars. In addition,

pure hydrogen is not abundant enough to provide power forall the cars on the road today. Instead, hydrogen wouldneed to be extracted from other substances, a process thatrequires energy and produces pollutants.

In an IGCC plant Hydrogen is produced as byproductwithout causing pollution and consuming extra energy

Advantages of IGCC


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Higher Output Using syngas in a gas turbine increases its

output, especially when nitrogen from anoxygen blown unit is fed to the turbine. Thus

a turbine rated at 170MW when fired onnatural gas can yield 190MW or more onsyngas .

Furthermore, output is less dependent onambient temperature than is the case withnatural gas.

Advantages of IGCC


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Unit Size A number of demonstration units, mainly around

250 MW size are being operated in Europe and theUSA. Most use entrained flow and are oxygenblown, and one is based on a fluidized bed, and isair-blown.

The 235 MW unit at Buggenum in theNetherlands , started up in 1993.

Three plants are in the USA at Wabash River inIndiana; Polk Power near Tampa in Florida andPion Pine in Nevada.

The largest unit is that at Puertollano in Spainwith a capacity of 330 MW.

Advantages of IGCC


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Lesser Area Requirement

Compact Process No Requirement of Ash Handling

System & Ash Dykes

Advantages of IGCC


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Advantages of IGCC

Less Solid waste and water use

Solid Wastes Less Volume : IGCC produce about half the solid

wastes of conventional coal plants.

Better Form : IGCC solid wastes are less likely toleach toxic metals than fly ash from conventionalcoal plants because IGCC ash melts and is vitrified

(encased in a glass-like substance). Water Use

Less Water : IGCC units use 20%-50% less water than conventional coal plants and can utilize drycooling to minimize water use.


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For Developing Countries

Entrained IGCC technologies are suitable for low-ashcoals. High-ash coals, such as those in India, wouldrequire fluidized-bed gasification processes.

The primary constraints to the application of gasificationand IGCC plants in developing countries are that thetechnology needs further demonstration, the costs arehigher than those of competing technologies, and the factthat environmental regulations in developing countries donot require the high SO2 removal and low-NOxemissions achieved by IGCC.

Kyoto Protocol


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IGCC in NTPC

FR shall be prepared for the IGCC projectat Dadri Pursue with BHEL for submitting the FR

for the other IGCC demo project Complete techno economic study of

Underground Coal gasification (UCG) shall be taken up. Possible locations could be

Pakri Barwadih and Singrauli area


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Barriers to Deployment : IGCC Power Industry Culture

This is a chemical plant. Power companiesunderstand combustion, not chemical units.

Perceived financial risk

Technology unfamiliarised Why build an IGCC if you can get a permit

for a conventional coal plant?


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Pioneer ing Gas i f i c at ion Plan t s

First major use of coal gasification to generate electricpower : Southern California Edison's experimentalCool Water project near Barstow, California, United

States

Took place in the mid-1980s

Capacity : 100MW

Technical foundation for future integrated gasificationcombined cycle (IGCC) power plants


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World's largest single traingasification combined cycle plant :

The Wabash River CoalGasification Repowering Project,

West Terre Haute, Indiana, UnitedStates

The plant can generate 292 MW ofelectricity -- 262 MW of which aresupplied to grid

The plant started full operations inNovember 1995


In 2002 DOE approved plans to site the world's first clean coaltechnology-powered fuel cell.


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Biggest Boost in IGGCThe Tampa Electric's PolkPower Station near Mulberry,Florida, United States

Capable of generating 313MWof electricity 250MW of whichare supplied to the electric grid

operating since 1996

Removes more than 98 % ofthe Sulfur in coal, converting itto a commercial product.


Nitrogen oxide emissions are reduced by more than 90 %


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Pioneer ing Gas i f i c at ion Plan t sAn American dreamThe Dakota Gasification Company, United States

The 1970s energy crisis spawned avision of greater U.S. energy

independence.The Synfuels plant began operatingin 1984 and today produces more

than 54 billion standard cubic feet ofnatural gas annually..

In addition to natural gas, the Synfuels plant producesfertilizers, solvents, phenol, carbon dioxide, and otherchemicals.


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Types o f Coa l Gas i f i c a t i on Reac t o r s

T h i s s ho w s t h e t h r e e m a i n c o a l g a s i fi c a t i o n p r o c e s s e s .

FIXEDBED

FLUIDIZEDBED

ENTRAINEDFLOW

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