By M.V. RadhakrishnanANSALDOCALDAIE Boilers India Private Limited,

Conference – ENERGEX 2008 Date : 26-09-2008

3 Nos. 660 MW – coal fired Supercritical

INTRODUCTION

ANSALDO CALDAIE with consortium of Hitachi was awarded the boiler contract on 1 Dec 2004

Torrevaldaliga North- Power Station

CUSTOMER : ENEL POWERCONTRACT : LSTK

OVERVIEW OF HISTORY

Total gross electric power (Mwe) : 2,640  Net efficiency 39% SH outlet temp. 540°C RH outlet temp. 540°C SH outlet pressure 253 bar Fuel oil with 0.23% sulphur content Flue gas treatment

FGD NOSCR YES Filters electrostatic YES

  Emission limits

SO2 mg/Nm3 guaranteed (Monthly average) 400NOx mg/Nm3 guaranteed (Monthly average) 200Dust mg/Nm3 guaranteed (Monthly average) 50

Source : ENEL data

4 X 660 MW oil fired supercritical units

Start-up between 1984 and 1986

 

OVERVIEW OF HISTORY

DRIVING FACTORS FOR CONVERSION

FUEL COST BEING HIGHER

LIFE OF PLANT EXAHUSTED

PRESENT STRINGENT EMISSION NORMS

REDUCTION OF GENERATION COST

KEY CHALLANGES

MEETING EU NEW EMISSION NORMS

UTILIZING SOME OF EXISTING PLANT HARDWARES

WIDE VARIETY OF COALS ##

SPACE CONSTRAINTS FOR STORAGE,ERECTION

## To maximize the usage of geographical location of plant near port

FEATURES OF NEW BOILER

Divided back pass with biasing dampers for RH outlet temp control

Spiral-wound waterwall tubes

Even heat absorption uniform water temp

distribution at outlet; Adequate mass velocity adequate margins against

DNB occurrence; Flow stability; Moderate pressure drop.

Start up and low load system Separators Water collecting vessel Recirculation pump Lower start up heat loss Ensures adequate cooling flow at

low load (below BENSON load)

FEATURES OF NEW BOILER

Boiler Parameters :

Unit type : Super Critical

SHO flow : 1918 t/h

SHO temp : 604 deg c

SHO pr : 252 bar

FW temp: 313 deg c

RH in / out : 370 / 612 deg c

RH flow : 1576 t/h

RH pr. : 58 bar

Furnace type : Balanced draft

Water wall : Spiral / Ribbed

Size : 22.5 m x 14.2 m

SH / RH stages : 3 / 2

SH temp control : Spray attemp.

RH temp control : Gas biasing

Economiser : Fin tubes

Fuel :

Design Fuel : COAL (South African)

Characteristics : HHV 26.4MJ/kg, Ash 13.6 %, Moisture 7.4 %

Start-up fuel : Natural Gas

Source of coal : Indonesia, Australia,South America,Poland, China

FEATURES OF NEW BOILER

Boiler Aux:

Mills : 5+1 (with rotary classifierBurners : Opposed wall - Low Nox

with OFAFans : 2 FD(axial)

2 PA(Radial) 2 ID (existing)

AH : 2 Nos. Tri-sector Lungstrom type

SB : Wall blowers Retractable for conv. Pass.(Medium : Air / SH steam)

SCR :

Outlet Nox : < 85 mg/Nm^3 (6% O2)

Catalyst type : Plate (can accommodate Honey comb also)

Reactor : Vertical downflow

Start-up philosophy:

At start-up & below 25 % load, steam water mixture is separated in the separator vessel & water flowing back to storage tank is re-circulated in economiser & furnace tubes by re-circulation pump.

Dismantling of existing oil fired boilers, SCR & precipitators

Installation of new boilers & relating auxiliaries , critical piping 

Installation of new SCR systems 

Installation of new FGD systems (By Owner)

Installation of sleeve filters  (By Owner)

Installation of new ash removal systems (Fly ash by owner)

Installation of closed remote controlled coal bunkers

Construction of two docks

MAJOR CONTRACT ACTIVITIES

BOILER ISLAND SUPPLIES

BOILER PROPER (PR. PARTS AND START-UP SYSTEM)

STEEL STRUCTURES FOR BOILER, BUNKER BAY AND SCR 

REGENERATIVE AIR HEATERS (trisector type) 

FD FANS (axial type) and PA FANS (radial type) 

COAL BUNKERS 

COAL PULVERIZING AND FIRING SYSTEM 

NATURAL GAS START-UP AND WARM-UP FIRING SYSTEM 

SCR SYSTEM 

BOTTOM ASH REMOVAL SYSTEM (DRY TYPE) 

CRITICAL PIPING (from boiler headers to steel structures boundary)

PLANT PFD

PFD – TREATMENT

EmissionLimits according to

Italian lawTorrenord oil fired

units

European regulation for new plants(In force since

1/1/2008)

Limits as per authorization for

Torrenord coal fired plant

SO2mg/nm^3

 400

 200

 100

Noxmg/nm^3

 200

 

 200

 100

Dustmg/nm^3

 50

 30

 15

A LOOK AT EU NORMS

Emissions reduced bySulphur oxide (SO2) - 82%

Nitric oxide (Nox) - 61%

Dust - 82%

BEFORE & AFTER CONVERSION

Source : Enel data

Before AfterGross power,MW 2640 1980Cycle Efficiency 39 % 45 %Fuel FO Coal

CONTRACT SCHEDULE MILESTONES  MONTHS  UNIT #1 PAC* 43 MONTHSUNIT #2 PAC 47 MONTHSUNIT #3 PAC 53 MONTHS

  

SCHEDULE BOILER WTS.

PR. PARTS 7000 T

NON. PR. PARTS 12000 T

TOTAL BOILER 26000 T

* Provisional Acceptance Certificate

CONSTRAINTS ENCOUNTERED

RAW MATERIALS FOR PR. PARTS PARTICULARLY HIGH ALLOY STEELS – T91, T92

MAIN STEEL STRUCTURAL COMPONENTS WITH HEAVY THICKNESS PLATES

COMPLEX AND COMPACT BOILER LAY-OUT DUE TO THE LIMITED SPACE

LIMITED MATERIAL STORAGE & PRE-ASSEMBLY AREAS

LIMITED SITE ROAD ACCESS

ERECTION CONSTRAINSTS DUE LACK OF ACCESS 

PLANT TODAY

Thank YouThank You