cfb presn-ntpc11.07.06

Presentation on CFBC Boilers

FBC & HRSGBharat Heavy Electricals Limited TIRUCHIRAPALLI

Welcometo

Presentationon

CFBC Boilers



CFBC Development Journey• Test Facility installed – 1991

• Collaboration with LLB ( LEE ) – 1993

• Technology transfer/Training of Engineers - 1996

• First non –reheat boiler (175 t/h ) installed at BILT , Bhigwan - 1998

• First Utility reheat boiler ( 2x125 MW ) installed at SLPP , Mangrol - 1999

• Testing of Lignite – 2001

• 125 MW order received from RVUNL, Giral – 2003

• 75 MW order received from GEB, Kutch – 2004

• 2 x 135 t/h order received from M/s Gujarat Ambuja cement - 2004

• 2 x 250 MW order received from Neyveli Lignite Corporation – 2005

• 125 MW repeat order received from RVUNL, Giral – 2005

• 2 x 125 MW order received from NLC – Barsingsar firing Rajasthan Lignite– Oct 2005

• 2 x 125 MW repeat order received from SLPP – March 2006



Basic Flow Diagram of CFBC Boiler

ID Fan

SECONDARYAIR



Advantages of CFBC

Simplified Fuel Preparation and feeding (No Pulveriser) In-Situ SOx and NOx control Oil support for load below 30% and start up only Slag-Free Combustion. Dry ash powder only FSSS avoided. Burner Management for Start-Up Burner

only Lower Temperature / Less Intense (no flame)

Combustor Environment Suitable for using wide range of fuels in the same boiler Suitable for fuels which are difficult to burn High Carbon Burn-out (Very low carbon in ash)



Why Fluid Bed Combustion ?



SOx Control

• Sulphur in fuel captured in combustor by addition of limestone

• Ca/S Molar Ratio varies between 1.5 to 2.5 depending on the Limestone Quality

• Expensive (FGD) add-on equipment avoided. Reliability improved



SOSO22 Control Reactions Control Reactions

• Straightforward method - Limestone addition along with fuel into combustor

• Reactions

S + O2 SO2

CaCO3 CaO + CO2 (Calcination)

CaO + SO2 + 1/2 O2 CaSO4 (Sulphation)



Limestone Requirement Limestone Requirement

Temperature

Lim

esto

ne R

equi

rem

ent



Formation of NOx and Control

• NOx formation Thermal NOx - Nitrogen in Air Fuel NOx - Nitrogen in Fuel

• Thermal NOx depends on Combustion temperature

In FBC boilers, the Combustion temperature is around

850°C, hence Thermal NOx is negligible

• Fuel NOx depends on excess air levels & Staging

In addition to low excess air levels, the combustion air is

staged. Hence Fuel NOx is also low



Spiess Valve

Advantages of FBHE



Distinct Advantages of FBHE

Elimination of heat transfer bundle / panel in combustor

Very Low carbon in ash and Limestone consumption even at part load due to Optimum combustor temperature (about 850 Deg C )

Better fuel flexibility due to provision for adjusting heat absorption

Higher efficiency and reduced NOx emission even at part load due to constant excess air

Unique RH temperature control option



Fuel Quality / Load

Com

b.

Tem

p.

Hea

t d

uty

Combustor

Conv. Pass

With FBHE

FBHE

Without FBHE



• Fuel Coal (Imported+Indian)

• Commissioned March 1998

• Total hours logged 65,000

• Minimum load achieved

(without Oil support) 20 % MCR

• Controllability Range (achieved) 30 to 100%

• Generally in Continuous operation between planned annual stoppages

SINARMAS 175 t/h CFBC Boiler



Arrangement (Elevation) of Bilt Graphics CFBC Boiler



Location : Mangrol , Surat Dt , Gujarat

Fuel : Lignite ( 50 % M & 2.5 %S)

HHV - 2500 to 5500

Total hours logged : 65,000

Boiler Parameters

SH Steam : 390 T/H, 132 ATA, 540 0C

RH Steam : 350 T/H, 32.5 ATA, 540 0C

SLPP 2 x 125 MW CFBC BOILER



Arrangement (Plan) of SLPP CFBC Boiler



Arrangement (Elevation) of SLPP CFBC Boiler



View of 2 x 125 MWe SLPP



SLPP - Lignites Used

Fuel Design Actual

Fixed Carbon % 14 - 40 18 - 33Volatile Matter % 25 - 44 21 - 26Moisture % 10 - 50 41 - 48Ash % 7 - 48 4 - 8Sulphur* % 0.36 – 2.5 0.3 - 2

HHV kcal/kg 2500 -5500 2300 - 4775



SLPP Performance

Fuel Design Actual

Carbon % 43.30 30.75Hydrogen % 3.14 3.48Sulphur % 1.20 (2.5) 1.18Nitrogen % 0.81 0.43Oxygen (by diff.) % 8.53 7.61Moisture % 24.00 42.44Ash % 19.02 14.10

HHV kcal/kg 4250 3090Chlorine content in Lignite Not identified 0.3-0.4%



RVUNL – Giral 125 MW



Comparison of SLPP – Giral (Boiler parameters )

Parameter Unit SLPP Giral

Unit Rating MW 125 125

Type of Circulation Natural Natural

SH/RH Flow t/h 390 / 350 405 / 336

SH/RH Pres. kg/cm2 132 / 30.5 132 / 34

SH/RH Tem. Deg C 540 / 540 540 / 540

FW Tem. Deg C 235 237



Lignite Analysis - ComparisonSLPP Giral

Proximate Analysis (% by weight) Moisture 24 10-50 40

Ash 19.02 7-48 15Volatile Matter 32.52 25-44 20Fixed Carbon (by diff.) 24.46 14-40 25HHV, kcal/kg 4240 2500-5500 3000

Ultimate Analysis (% by weight)Carbon 43.330.09Hydrogen 3.14 2.24Sulphur 1.2 (max 2.5) 6.00Oxygen 8.55 6.27Nitrogen 0.81 0.4Moisture 24.0 40.0Ash 19.02 15.0



Limestone Analysis - Comparison

SLPP GiralAnalysis (% by weight)

CaCO3 85.23 96.8

MgCO3 1.18 1.2SiO2 8.65 1.15Moisture 2.05 0.28Others 2.89 0.57



Giral – Design Evolution



Giral CFBC Boiler Design - Evolution

• About 50 feedbacks from the operational experience from SLPP and BILT Graphics

• Learnings from 158 SARs from SLPP and Bilt Graphics incorporated

• Discussions with Manufacturing and OP&C groups

• Discussions with Erection Group - PSWR



250 MW CFBC Flow Schematic



250 MW CFBC Boiler

CONVECTIVE PASS

CYCLONES

SEC. APH( REGEN )

FBHE

SPECIALCOMBUSTOR

COAL BUNKERS



General Arrangement of 250 MW CFBC boiler

cfb presn-ntpc11.07.06

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