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Fluidized Bed Technologies for High Ash Indian Coals – A Techno-Economic Evaluation . Dr. D.N. Reddy, Director Dr. V.K. Sethi, Research Adviser Centre for Energy Technology, University College of Engineering (Autonomous) Osmania University, Hyderabad – 500 007, India.

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fluidized bed technologies for high ash indian coals a techno economic evaluation

Fluidized Bed Technologies for High Ash Indian Coals – A Techno-Economic Evaluation

Dr. D.N. Reddy, Director Dr. V.K. Sethi, Research AdviserCentre for Energy Technology, University College of Engineering (Autonomous) Osmania University, Hyderabad – 500 007, India.

indian power sector towards sustainable power development
INDIANPOWER SECTOR - TOWARDS SUSTAINABLE POWER DEVELOPMENT
  • Total Installed Capacity … 103,000 MW
  • Thermal Generation … over 70 %
  • Although no GHG reduction targets for India but it has taken steps through adoption of Combined cycles, Co-generation, Coal beneficiation,Plant Performance optimization
  • Long term measures like adoption of Clean coal technologies; IGCC, FBC, Supercritical technologies
  • Clean Development Mechanism (CDM) conceived to reduce cost of GHG mitigation, while promoting sustainable development as per Framework Convention on Climate change (FCCC) is being implemented
significance of the present study
SIGNIFICANCE OF THE PRESENT STUDY...
  • Environmentally benign Clean Coal Technology of advanced Fluidized Bed Combustion is an ideal technology for high ash coals
  • Statutory use of washed coal for TPS >1000 km from the pit head calls for setting up of washeries > 85 Million tons / annum.
  • Use of Washery rejects & Middling for Power generation calls for adoption of CFBC technology
  • The present paper deals with the techno-economic and transfer of technology aspects of Clean coal technology in general and CFBC in particular for inferior coals & in refurbishment of old polluting plants
energy efficient technologies

Energy Efficient Technologies

Technologies on Anvil for Power generation using high ash Indian coals:

Supercritical (SCR) & Ultra – supercritical (USC)

Integrated Gasification Combined Cycle (IGCC)

Fluidized Bed Combustion

slide5

VISION 2020

PROGRAM

Gasification using + fluidized bed, moving bed or Entrant bed Gasifiers

In-combustion Clean-up Fluidized bed combustion (CFBC, PFBC, AFBC)

Post combustion Clean-up-Desulfurization(FGC systems) Supercritical

Pre combustion Clean-up 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.

slide6

o

Super Critical PC Power Plant (15 C Amb.)

60

Super Critical PC Power Plant (Indian Condition)

o

IGCC (15 C Amb)

55

IGCC (Indian Condition)

Sub Critical PC Power Plant (Indian Condition)

50

o

1500 C

o

1300 C

o

623 C

Net Thermal Efficiency (%)

o

600 C

45

o

566 C

40

Ceramic gas

turbine

o

1184 C

o

650 C

35

o

540 C

30

1995

2000

2005

2010

1990

Year of commercial use

Fig.5 EFFICIENCY IMPROVEMENT FORECAST

CONVENTIONAL Vs IGCC(Courtesy BHEL)

the principal advantages of supercritical steam cycles are

The Principal advantages of supercritical steam cycles are :-

Reduced fuel costs due to improved thermal efficiency

CO2 emissions reduced by about 15%, per unit of electricity generated, when compared with typical existing sub-critical plant

Well proven technology with excellent availability, comparable with that of existing sub-critical plant

Very good part-load efficiencies, typically half the drop in efficiency experienced by sub-critical plant

Plant costs comparable with sub-critical technology and less than other clean coal technologies.

Very low emissions of nitorgen oxides (Nox) sulfur oxide (Sox) and particulate achievable using modern flue gas clean-up equipment etc.

front line issues are to be reolved

Front line issues are to be reolved

Development of high temperature creep resistant alloy steels

Turbine material development

super critical technology indian perspective

Super Critical Technology- Indian Perspective

Mega power policy of setting up of coal fired supercritical/Ultra Supercritical units at pit-head

Cost of generation is least for pithead washed coal-fired unit amongst all other supercritical units.

The optimum parameter for Indian conditions is suggested as 246 kg/cm2 & 538/566C.

Based on transfer of technology model as per logic diagram (shown next) the velocity of transfer of technology for supercritical units is 2 ½ from the year 2000.

slide10
IGCC TECHNOLOGY ...
  • 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.

slide11
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
slide12
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.
  • Technology transfer related issues and techno-economic analysis vis-à-vis CFBC are covered in the paper
slide13

Identified R&D Areas in IGCC are:

  • Process optimization of selected gasification process
  • 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
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 by-products 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.
slide15
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 (40-50% Ash) Indian Coal
technology related issues in igcc
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
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 on technology aspects of igcc
SOME IMPORTANT FINDINGS ON TECHNOLOGY ASPECTS OF IGCC...
  • Reactive solid sorbent de-sulfurization combined with hot gas cleaning through ash and sorbent particle removal provides for higher energy efficiency to the extend 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
slide19
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.
a generalized scheme for transfer of technology
A GENERALIZED SCHEME FOR TRANSFER OF TECHNOLOGY
  • The first step in the scheme is to disintegrate the Power plant concept into components, sub systems, production chain, production technologies
  • Next step is the Value addition to each element of the production chain
  • Assessment of necessity of Import and Calculation of indigenous production share
  • Calculation of Velocity of the Transfer of Technology both at normal pace as well as accelerated pace
slide22
Typical results of the velocity of TOT are : -

(With year 2000 as base)

  • IGCC (oxygen blown) - Pet coke

Normal pace ---- 5 years

Accelerated ---- 2  years

  • IGCC (Air Blown) ---- Coal

Normal pace ---- 7 years

Accelerated ---- 5 years

)

some findings related to transfer of technolgoy tot
SOME FINDINGS RELATED TO TRANSFER OF TECHNOLGOY (TOT)
  • 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
  • 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
circulating fluidized bed combustion

Circulating fluidized Bed Combustion

Circulating Fluidized Bed Combustion (CFBC) technology has selectively been applied in India for firing high sulphur refinery residues, lignite, etc.

In the overall terms the CFBC is superior to PC as follows:

- Lower NOx formation and the ability to capture SO2 with limestone injection the furnace.

- Good combustion efficiencies comparable to PC

-The heat transfer coefficient of the CFB furnace is nearly double that of PC which makes the furnace compact.

-   Fuel Flexibility: The CFB can handle a wide range of fuels such as inferior coal, washery rejects, lignite, anthracite, petroleum coke and agricultural waste

cfbc vs other clean coal technologies

ITEM

CFBC

PF+FGD/SCR

IGCC

Cycle Eff. %

34.8

36.7

41-42

Relative Capital Cost/kW

1.0

1.03-1.19

1.15-1.42

Relative O&M Cost/kW

1.0

1.49

0.8-0.98

¨CFBC Vs Other Clean Coal Technologies

At present pulverized fuel firing with FGD are less costly than prevailing IGCC technology. However, firing in CFB Boiler is still more economical when using high sulfur lignite and low-grade coals and rejects.

revamping of old polluting pc boilers by cfbc boilers

Revamping of Old Polluting PC Boilers by CFBC Boilers

Renovation & Modernization (R&M) and Life Extension (LE) of old power plants is a cost-effective option as compared to adding up green field plant capacities.

Growing environmental regulations would force many utilities within the country to go for revamping of these polluting old power plants using environmentally benign technology.

A mere refurbishment by the same type of new boiler would not provide the right solution today. There is desperate need to revamp aging power boilers in India with environmentally friendly technology, which will improve the thermal as well as environmental performance.

CFBC offers a promising technology on this front. This calls for boiler sizing within the constraints of an old polluting plant

Some representative results follow ...