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IGCC for Power generation
N.T.P.C GAS PLANT DADRI
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Total installed capacity over 1,00,000 MW
Thermal power generation has emerged as theprincipal source of electric power in Indiacontributing to about 70%
Coal fired thermal stations are inpredominance and share about 84% of thetotal thermal installed capacity.
It is prudent and economical to developmethods and process for efficient utilization oflow-grade Indian coals for power generation.
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Gasification of coal is the cleanest way of utilizationof coal, while combined cycle power generation givesthe highest efficiency.
Integration of these two technologies in IGCC power
generation offers the benefits of very low emissionsand efficiencies of the order of 44-48%.
The comparative indices show that in case of IGCC,
emission of particulate, NOx and SOx are:7.1%, 20% and 16%, respectively, of thecorresponding emissions from PC plant.
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Environmental performance of IGCC thusfar exceeds that of conventional and evensupercritical plants.
Three major areas of technology that willcontribute to improvements in IGCC are :
hot gas de-sulfurisation
hot gas particulate removal advanced turbine systems
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Commercialization of IGCC needs technologydemonstration at an intermediate scale of about
100 MW to address the issues such as:hot gas clean ups and system optimization and
to establish reliability and performance.
This would also enable to design an optimummodule for air blown gasification, which inmultiples would constitute a commercial sizeplant in the range of 300-600 MW.
The present study addresses these issues andsuggests suitable technologies for Indian Coals.
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VISION 2020
PROGRAM
Post combustion Clean-up-Desulfurization
(FGC systems) Supercritical
In-combustion Clean-upFluidized bed
combustion (CFBC,PFBC, AFBC)
Gasification using +fluidized bed, moving bedor Entrant bed Gasifiers
Pre combustion Clean-up beneficiation/washing
Technologies for utilization of Coal for Power Generation with minimalpollutants discharged to the atmosphere (Reduced CO2, Sox, Nox,
SPM) at high conversion efficiency.W.C.I.
CLEAN COALTECHNOLOGIES
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Gasifier Gas Cleanup Gas turbine
HRSG Steam TurbineSteam
Hot Gas
Power
BFW
Steam Flue Gas to Stack
Steam
Coal
Ash Sulfur Air
Fuel gas
Compressed Air
Schematic Layout of the
Integrated Gasification Combined Cycle
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Comparison of various Power PlantsPower Plant
ConceptsMajor Components Efficiency %
Cost per
MW (Rs.
Crore/MWPC fired
Thermal
Boiler, Steam turbine, Coal
handling and other BOP34-37 3.8-4.0
CC PlantGas turbine, Steam turbine, Waste
hear recovery boiler40 3.2-3.4
IGCC (Coal)
Coal preparation unit, gasifier,
steam turbine, Gas cleaning GT,
WHTSG
46* (estimated) 4.86-4.95**
IGCC (Pet
Coke)
Air separation unit GT, ST,
WHRSG, Gas Clean up
48* (with G/H
class Gas
turbines)
4.25-4.30**
Super CriticalAs for PC fired Thermal plus spiral
tubes and high temp alloys37.5-39.5 3.95-4.10
* High efficiency coupled with low emission (SPM: 7%,
Sox:16%, Nox:21% of corresponding PC Plant)
** For Indigenous Units through systematic transfer of Technology
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Identified R&D Areas are:
Process optimization of selected gasificationprocess
Improvement of design and reliability of plantcomponents & Resource Optimization
Optimization of overall plant heat integration and
layout
Hot gas cleanup
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COAL GASIFICATIONSELECTION OF
GASIFICATION PROCESS
The fluidised bed process has many technical and environmentaladvantages over the moving bed process, such as,
The fluidised bed can use any amount of fines whereas inthe moving bed only 10% of fines can be used.
In the fluidized bed process, hydrocarbon, liquid by-products such as tar, oil and gas-liquor are not producedand, hence, the pollution is reduced.
High ash coals can also be successfully gasified in thefluidised bed.
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BENEFITS EXPECTED FROM IGCC
India endowed with large coal reserves over 200 billion
tonnes.
Environmental benefits due to higher efficiency ofconversion and reduced SPM, SOx, NOx levels can be
achieved using coal based IGCC technology.
Retrofit/Re-power options for gas based CCGT plantsby installing only coal based gasifiers are cost effective
(opportunity cost low) and are environmentally benign.
Adoption of IGCC technology in India has Global aswell as National benefits.
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IGCC DEVELOPMENT PROGRAM IN INDIA
Pioneering work on IGCC development in India taken upby BHEL in early eighties.
Major Mile Stones
Choice of gasification for high ash coals by BHEL
6.2 MW IGCC demonstration plant established by BHELboth with moving Bed and Fluidized bed.
Coal characterization by BHEL & IICT for gasificationapplication.
Intensive data generated by IICT on oxygen-steamgasification in their moving bed gasifier.
Task force CEA, CSIR, NTPC & BHEL constituted toassess technological maturity & financial requirement fora green field IGCC plant of 100 MW capacity at Dadri(NTPC).
BHEL, CSIR & NTPC prepared proposal for setting up ofthis 100 MW IGCC demonstration plant.
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Experience on the fluidized bed process is,very limited in the country.
Internationally, the experience gained so far isonly for low ash coals.
Thus there is a need for taking up extensiveR&D on IGCC Pilot Plant using high ash (40-50% Ash) Indian Coals.
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Technology-related issues in IGCC
Design of Advanced gasifiers (optimum gas
composition, optimum scale-up etc.)
Hot gas cleaning (de-sulphurisation and particulateremoval)
Advanced gas turbines (blade design to sustain ash
laden gas)
CO2 emission abatement in IGCC Power Plants
Operating conditions of IGCC plants in transient stage
Configuration of an optimized system for IGCC
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Fuelrelated issues
In a Raw Pet-Coke and refinery residue based IGCC Plant
System optimization, particularly the balance of plant
Optimized Heat balance diagrams
Scaling up of gasifiers to optimum size
In a Coal/Lignite based IGCC Plant Process & Plant conceptual design
De-sulfurization of syngas of high sulfur coal and lignite
Optimized Heat balance diagrams
Super critical Vs IGCC in Indian context
Application of ASME PTC-47 code for IGCC for high ash coals and
lignite
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SOME IMPORTANT FINDINGS
Reactive solid sorbent de-sulfurization combined with hot
gas cleaning through ash and sorbent particle removal
provides for higher energy efficiency to an extent of 4-7%.
The current Capital cost of building an IGCC power plant is
of the order of Rupees 6 crore/ MW.
Improvements in hot gas cleaning coupled with Cycleoptimization shall bring down the cost drastically to a level
of $ 1000/kW or about Rupees 4.5 crore/MW
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The efficiency of refinery bottom based IGCC unit will be about2% higher than that of coal based IGCC unit.
Refinery based IGCC plants - Advantages
Co-generation of steam
Co-production of hydrogen gas & recovery of sulfur element
No use of limestone, as required for CFBC technology
No requirement of extra land for disposal of solid waste
In the long run the refinery based IGCC technology is equallyattractive to coal based IGCC from economic andenvironmental considerations.
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SOME FINDINGS RELATED TO
COMMERCIALIZATION OF TECHNOLGOY
At present it may be prudent to implement the project in
phased manner to absorb the risk of gasifier in the total
project wrap-up guarantees fig. 1
A Technology Transfer model for determination of velocity
of Transfer of Technology (TOT) is an useful tool for TOTof a frontier technology from a developed economy to a
developing economy fig. 2
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Typical results of the velocity of TOT are : -
(With year 2000 as base)
IGCC (oxygen blown) - Pet cokeNormal pace ---- 5 years
Accelerated ---- 2 years
(Fig 3)
IGCC (Air Blown) ---- Coal
Normal pace ---- 7 years
Accelerated ---- 5 years
( Fig 4)
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Fig. 1
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Fig. 2
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Fig. 3
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Fig. 4
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Fig.5 EFFICIENCY IMPROVEMENT FORECAST
CONVENTIONAL Vs IGCC
60
55
50
45
40
35
301990 1995 2000 2005 2010
Year of commercial use
NetTherm
alEfficiency(%)
Ceramic gas
turbine
566 Co600 Co
623 Co1300 Co 1500 C
o
540 Co
650 Co1184 Co
IGCC (15 C Amb)IGCC (Indian Condition)
Super Critical PC Power Plant (15 C Amb.)o
Super Critical PC Power Plant (Indian Condition)o
Sub Critical PC Power Plant (Indian Condition)
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