Transcript IGCC for Power generation – an environmentally benign and

IGCC for Power generation
&
By
Dr. D.N. Reddy, Director
Er. K. Basu, Adviser
Dr. V.K. Sethi, Research Adviser
Centre for Energy Technology,
University College of Engineering (Autonomous)
Osmania University, Hyderabad – 500 007,
India.
– Total installed capacity over 1,00,000 MW
– Thermal power generation has emerged as the
principal source of electric power in India
contributing to about 70%
– Coal
fired
thermal
stations
are
in
predominance and share about 84% of the
total thermal installed capacity.
– It is prudent and economical to develop
methods and process for efficient utilization of
low-grade Indian coals for power generation.
– Gasification of coal is the cleanest way of utilization
of coal, while combined cycle power generation gives
the highest efficiency.
– Integration of these two technologies in IGCC power
generation offers the benefits of very low emissions
and 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 the
corresponding emissions from PC plant.
– Environmental performance of IGCC thus
far exceeds that of conventional and even
supercritical plants.
– Three major areas of technology that will
contribute to improvements in IGCC are :
 hot gas de-sulfurisation
 hot gas particulate removal
 advanced turbine systems
– Commercialization of IGCC needs technology
demonstration 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 optimum
module for air blown gasification, which in
multiples would constitute a commercial size
plant in the range of 300-600 MW.
– The present study addresses these issues and
suggests suitable technologies for Indian Coals.
VISION 2020
PROGRAM
In-combustion Clean-up
Fluidized bed
combustion (CFBC,
PFBC, AFBC)
Gasification using +
fluidized bed, moving bed
or Entrant bed Gasifiers
Post combustion Clean-upDesulfurization
(FGC systems) Supercritical
Pre combustion Cleanup beneficiation/washing
CLEAN COAL
TECHNOLOGIES
Technologies for utilization of Coal for Power Generation with minimal
pollutants discharged to the atmosphere (Reduced CO2, Sox, Nox,
SPM) at high conversion efficiency……….W.C.I.
Schematic Layout of the
Integrated Gasification Combined Cycle
Steam
Flue Gas to Stack
BFW
HRSG
Steam
Steam Turbine
Steam
Coal
Compressed Air
Hot Gas
Gasifier
Fuel gas
Gas Cleanup
Gas turbine
Power
Ash
Sulfur
Air
Comparison of various Power Plants
*
Power Plant
Concepts
Major Components
Efficiency %
Cost per
MW (Rs.
Crore/MW
PC fired
Thermal
Boiler, Steam turbine, Coal
handling and other BOP
34-37
3.8-4.0
CC Plant
Gas turbine, Steam turbine, Waste
hear recovery boiler
40
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 Critical
As for PC fired Thermal plus spiral
tubes and high temp alloys
37.5-39.5
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
Identified R&D Areas are:
– Process
process
optimization
of
selected
gasification
– Improvement of design and reliability of plant
components & Resource Optimization
– Optimization of overall plant heat integration and
layout
– Hot gas cleanup
COAL GASIFICATION – SELECTION OF
GASIFICATION PROCESS
The fluidised bed process has many technical and environmental
advantages over the moving bed process, such as,
– The fluidised bed can use any amount of fines whereas in
the moving bed only 10% of fines can be used.
– In the fluidized bed process, hydrocarbon, liquid byproducts such as tar, oil and gas-liquor are not produced
and, hence, the pollution is reduced.
– High ash coals can also be successfully gasified in the
fluidised bed.
BENEFITS EXPECTED FROM IGCC
• India endowed with large coal reserves over 200 billion
tonnes.
• Environmental benefits due to higher efficiency of
conversion and reduced SPM, SOx, NOx levels can be
achieved using coal based IGCC technology.
• Retrofit/Re-power options for gas based CCGT plants
by installing only coal based gasifiers are cost effective
(opportunity cost low) and are environmentally benign.
• Adoption of IGCC technology in India has ‘Global’ as
well as ‘National’ benefits.
IGCC DEVELOPMENT PROGRAM IN INDIA
• Pioneering work on IGCC development in India taken up
by BHEL in early eighties.
• Major Mile Stones
– Choice of gasification for high ash coals by BHEL
– 6.2 MW IGCC demonstration plant established by BHEL
both with moving Bed and Fluidized bed.
– Coal characterization by BHEL & IICT for gasification
application.
– Intensive data generated by IICT on oxygen-steam
gasification in their moving bed gasifier.
– Task force CEA, CSIR, NTPC & BHEL constituted to
assess technological maturity & financial requirement for
a green field IGCC plant of 100 MW capacity at Dadri
(NTPC).
– BHEL, CSIR & NTPC prepared proposal for setting up of
this 100 MW IGCC demonstration plant.
– Experience on the fluidized bed process is,
very limited in the country.
– Internationally, the experience gained so far is
only for low ash coals.
– Thus there is a need for taking up extensive
R&D on IGCC Pilot Plant using high ash (4050% Ash) Indian Coals.
Technology-related issues in IGCC
– Design of Advanced gasifiers (optimum gas
composition, optimum scale-up etc.)
– Hot gas cleaning (de-sulphurisation and particulate
removal)
– 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
Fuel – related 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
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 Cycle
optimization shall bring down the cost drastically to a level
of $ 1000/kW or about Rupees 4.5 crore/MW
 The efficiency of refinery bottom based IGCC unit will be about
2% 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 equally
attractive to coal based IGCC from economic and
environmental considerations.
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 TOT
of a frontier technology from a developed economy to a
developing economy
fig. 2
Typical results of the velocity of TOT are : (With year 2000 as base)
 IGCC (oxygen blown) - Pet coke
Normal pace
Accelerated
-------
5 years
2 years
(Fig 3)
 IGCC (Air Blown)
Normal pace
Accelerated
----------
Coal
7 years
5 years
( Fig 4)
Fig. 1
16
Fig. 2
1
Fig. 3
36
Fig. 4
1
Super Critical PC Power Plant (15 oC Amb.)
Net Thermal Efficiency (%)
60
Super Critical PC Power Plant (Indian Condition)
IGCC (15 oC Amb)
55
IGCC (Indian Condition)
50
45
566 oC
Sub Critical PC Power Plant (Indian Condition)
1500 oC
1300o C
623 oC
600o C
40
1184o C
650o C
35
Ceramic gas
turbine
540oC
30
1990
1995
2000
2005
2010
Year of commercial use
Fig.5 EFFICIENCY IMPROVEMENT FORECAST
CONVENTIONAL Vs IGCC