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Different aspects to consider selecting FGD type of technology

Power-Gen India & Central Asia, 19-21 April, 2012, New Delhi, India

Lars-Erik Johansson

© ALSTOM 2012. All rights reserved. Information contained in this document is indicative only. No representation or warranty is given or should be relied on that it is complete or correct or will apply to any particular project. This will depend on the technical and commercial circumstances. It is provided without liability and is subject to change without notice. Reproduction, use or disclosure to third parties, without express written authority, is strictly prohibited.

Agenda

• 1st topic Introduction and classification of FGD

• 2nd topic Different type of FGD with main features

• 3rd topic Different aspects for considerations

• 4th topic Examples of evaluations

• 5th topic Conclusions


Emissions to Air and its Effects


WHO air quality guidelines for major air pollutants


SO2 Emission Requirements (mg/Nm3)

U.S. 250 (50) (3-4 y) <200

W. Europe 400 <200

E. Europe 400 - Uncapped <400

Pacific Case-By-Case <400

Japan 170-860 <200

Taiwan 1430 <400

South Korea 100-200

China 100-200 (50)

NationalStandards

CurrentRequirement

Efficiencies requested from 80 % up to 98 %


First utility FGD in the world: London, England

• Battersea Power Station - 1935

•Used alkaline Thames river water to scrub SO2

•Scrubber was made of wood

•Worked fine – Stopped due to

the plume•Great London Smog o f 1952

•2008: Newly unveiled plan for Battersea

Power Station

•Battersea power station – site of first FGD


Classification of post-combustion FGD

• Wet systems- Operating at saturated conditions

- Using slurry or solution in the flue gas with nozzles to

create mass transfer between flue gas and liquid

• Complete dry systems- Introducing dry absorbent (lime or bicarbonate)

- Limited performance without controlling the temperature

• DFGD operation with controlled temperature- Spray dryer absorber – using a slurry

- Circulating Dry Scrubber or NID™ – using recycle solids in

combination with a fabric filter


Most common principles forFlue Gas Desulphurisation (FGD)

Flue Gas Desulphurisation

Open Spray Tower Lime/Lime Stone

Bubbling bed/Tray absorberLime/Lime Stone

FGD AbsorberSea water

Spray Dryer Absorber

Circulating Dry Scrubber/NID

Dry Options(DFGD)

WET FGD

Gypsum

Gypsum

None

Sulphite

Sulphite

End ProductFGD typeFGD options


Agenda





• 5th topic Conclusion


Limestone WFGD Process Diagram

•MAKE-UP

WATER

TANK

•CHLORIDE

PURGE

•HYDROCLONE

•BELT FILTER

•SPRAY TOWER

ABSORBER

•ELECTROSTATIC

PRECIPITATOR

•STACK

•WATER

•AIR

•LIMESTONE

•BALL MILL

•TO BALL

MILL

•FROM MW

TANK

•GYPSUM

REAGENT

PREPARATION

ABSORBER

DEWATERING


Limestone/Forced Oxidation

SO2

(Sulfur dioxide)

H2O(Water)

CaCO3

(Calcium carbonate, limestone)

O2

(Oxygen)

CaSO4•2H2O(Calcium sulfate,

gypsum)

CO2

(Carbon dioxide)

SO2 + CaCO3 + ½O2 + H2O →→→→ CaSO4•2H2O + CO2


Typical LS WFGD

•CPS Energy, J.K. Spruce Unit 2, US, 750 MW


DFGD – technology specific features

• Lime-based semi-dry FGD technology• Control the temperature to meet high performance• Multi-pollutant control: High efficiency removal of SO2,

SO3, PM, HCl, and HF• Fuel flexibility of up to 2.5% sulphur coal or higher

• Several types- Spray Dryer Absorber (SDA)

Slurry based

- Circulating Dry Scrubber (CDS)

Introducing water and recycle solids independently in one or several high velocity sections (venturi’s)

- NID™

Premixing of recycle solids and water



CaO + H2O -> Ca(OH)2 + heatSO2 + Ca(OH)2(s) -> CaSO3.½H2O(s) + ½H2O



Atomizing of slurry into small droplet by atomizing disc (shown) or two-media nozzles


NID™ Flow Schematics

Reactor

Mixing Zone

Injection Zone


NID-C Modular Concept

• Multiple, independently isolatable

modules• Dampers

- Upstream of reactor- Downstream of FF compartment

• Nominal gas flows corresponding

to 15 - 70 MWel per module

• Can be designed to achieve

emissions guarantees at full load

with one module out of service

Allows for Turn-Down up to 60% without Recirculation


Recent development using Modular Design (NID-C)

•Unit 1

•Unit

2

•Stack

Modularization Offers Arrangement Flexibility and adaption to larger sizes


Modular Design (NID-C)

• Shop fabrication drastically

cheaper than field fabrication

• Allows high degree of shop fabrication even with truck

shipment- Reactors

- Inlet ducts

- Day silos

- Mixers

- Hydrators

• Barge access allowsfurther pre-assembly

- Fabric filter compartments

- Inlet/outlet plenums

Modularization Lowers Construction Costs


DFGD, NID-C was most favourable evaluated, toward other technologies

Recent NID-C application

Location Indian River, US

Capacity 410 MW

Fuel Coal, 2,5 % S

SO2 removal 96 % (75 PPM)

Others HCl, SO3, HF

Particulate, Opacity

Start-up 2012


Sea Water Flue Gas Desulphurization (SWFGD)

FlueGas

DustCollector

SO

Absorber

Sea WaterTreatment

Plant

Air

TreatedSea Water

CleanFlueGas

Sea Water

Reheat

Equipment2

Sea Water


Sea Water Flue Gas Desulphurization (SWFGD)

SO2 + H2O ↔↔↔↔ SO32- + 2H+

(absorption)

H+ + HCO3- + ↔↔↔↔ CO2 + H2O

(neutralisation)

(oxidation)

SO32- + ½O2 →→→→ SO4

2-

• CO2

• H2O

• SO42-


Alstom SWFGD 3D Layout

Absorber Pump

Aeration Fan

ESP or FF

ID Fan Booster Fan

SWTPAbsorberGGH


Discharge seawater quality

Sea Water Treatment Plant is a key for good discharge quality


Haimen Power Plant

Location Haimen, P.R. China

Capacity 2 x 1000MW

Fuel Coal, 0.9 % S

Gas flow 3 426 000 Nm3/h

SO2 inlet 1960 mg/Nm3

(dry, 6% O2)

SO2 removal 95 %

Flue Gas Reheat GGH

Effluent pH >6.8

Start-up 2009

World’s Largest SWFGD for Unit Size


Agenda







Selecting FGD Technology

Economic aspects•Capital cost•Operating cost

Technical aspects•Sulphur removal

•Reliability

•Space requirements

Commercial aspects•Reliable supplier

•Proven technology

•Supplier guarantee


Selecting FGD technology – New or Existing

• Green-field- Space can be planned, but different technologies give

different layout demands

- Some (wet) FGD technologies must be complemented with

particulate separation

• Brown-field- Normally limitation in foot-print

- Existing AQCS-equipment and status have importance

- Reuse of stack

- Loss of revenue during installation

• Ready for retrofit- CO2 capture ready – space requirements

- Increased emission demands


Selecting FGD Technology - Emissions

• Emissions of SO2 and other acid components- Most technologies can handle the demands

• Liquid discharge- Access to release Cl rich water

• Particulate- DFGD technologies using fabric filters can handle the

particulate emissions

• Visible plume – dispersion of stack plume- DFGD operate at high temperature than wet systems

- Reheat might be needed for wet systems

- DFGD technologies have higher efficiencies on SO3 – to

meet low opacity


Selecting FGD Technology - Cost

• Absorbent material- DFGD needs quick lime with high quality to meet low

consumables and good control emissions

- Limestone, to be used within LS WFGD needs to be of

good commercial quality

- In case of sea water, access is needed – coastal areas

• NPV- All cost to be included in OPEX and CAPEX

- Discount rate and evaluation time

- High rate and long time favor technologies with relative high CAPEX and low OPEX

• Size of the plant- Consumptions is normally proportional to the size- Other operation normally less than proportional to the size

- Investment cost normally less than proportional to the size


Typical key parameters for different technologies - overview

Dry FGD Seawater FGD Limestone WFGDAbsorber NID or SDA Packed Tower Spray Tower

First Installation 1980 1968 1968

Features • Low investment cost

• Dry by-product

• Small footprint• Multi-pollutant

control

• No reagent• No by-product

• High efficiency spray zone

• Low cost reagent• By-product flexibility

Reagent Lime Seawater Limestone

By-product Landfill Seawater Marketable gypsum or landfill

Sulfur <4.5 % (NID) <1.5 % <6 %

Removal Efficiency

-98 % (NID) -98 % -99 %

Capital Cost 0.7X 0.8X X

Power Consumption (inc. booster fans)

0.7 % 0.7-1.5 % 1.0-2.0 %

Aborbent Cost €80/ton €0/ton €20/ton

By-product Cost €5-10/ton €0/ton €5-10/ton – disposal(€5/ton) – sale


Agenda







FGD Technology Selection - Overview

DFGD – NID technology has expanded the range to large plants


Example NPV calculation for different technologies

Each case must be evaluated with the specific conditions


Agenda







Conclusions

• Many technologies has during the years been developed with DFGD, LSWFGD and SWFGD as the preferred, most widely spread technologies

• All established technologies can meet the demands for SO2 removal for the Indian market

• All technologies have different consideration and often related to operation and capital cost transferred to NPV

• Specifically for low to medium range sulphur content, the DFGD and SWFGD will most probably be the preferred total evaluated technologies

Reliable technologies exist to meet the future market in INDIA, but each case must be evaluated


Questions ?

Thank You

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