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

Post combustion Clean-up-Desulfurization

(FGC systems) Supercritical

In-combustion Clean-up Fluidized bed

combustion (CFBC, PFBC, AFBC)

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

Pre combustion Clean-up beneficiation/washing

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.

CLEAN COAL TECHNOLOGIES

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 theIntegrated Gasification Combined Cycle

Comparison of various Power PlantsComparison 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 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 Critical As 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

Identified R&D Areas 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

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.

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 (40-50% 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 ---- 5 years

Accelerated ---- 2 years

(Fig 3) IGCC (Air Blown) ---- Coal

Normal pace ---- 7 years

Accelerated ---- 5 years

( Fig 4)

1616

Fig. 1

11

Fig. 2

36

Fig. 3

1

Fig. 4

Fig.5 EFFICIENCY IMPROVEMENT FORECASTCONVENTIONAL Vs IGCC

60

55

50

45

40

35

301990 1995 2000 2005 2010

Year of commercial use

Net

The

rma

l Effi

cie

ncy

(%)

Ceramic gasturbine

566 Co 600 Co623 Co

1300 Co 1500 Co

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)