AIR POLLUTION CONTROL ABATEMENT

FOR THERMAL (COAL PLANTS)

Leon van Wyk

Project Development Specialist, Lesedi, South Africa

• What is MES and why?

• Technologies available to comply with MES

• Design approaches required to meet compliance

• Closing remarks

PRESENTATION OUTLINE

• Lesedi evolved from Intens Engineering which was

founded in 1984 servicing Koeberg Nuclear Power

Station. We have since diversified into a major multi-

disciplinary engineering, procurement and construction

(EPC) company.

• We are projects orientated and technology agnostic

• Partnering for cost effective solutions whilst combining

owners engineering with design engineering to provide

effective solutions within a South African context

OVERVIEW OF LESEDI

• MES – Minimum Emission Standards evolved from scientific studies world

wide to understand the human and animal health considerations.

• Reportable emission gasses (criteria pollutants) all have a negative effect to

predominantly the respiratory system in humans and contributes to mortality

rates in affected regions.

• South Africa has two priority areas as classified by the Department of

Environmental Affairs – Highveld and Waterberg

• Mpumalanga is worlds worst affected NOX contaminated area according to

a recent study (Greenpeace)

• Pollutants and greenhouse gases are different and need to be managed

differently

WHAT IS MES AND WHY?

SOUTH AFRICAN PRIORITY AREAS

6

PM10: NOx:

SO2:

Graphs for the Highveld Priority Area

GREENHOUSE VS POLLUTANTS

• Greenhouse gasses affects global

warming

– CO2 biggest contributor

• Pollutants affects human health

– Major criteria pollutants (to be measured by

countries)• Particulate Matter, SO2, NOX, Mercury – not yet

legislated in South Africa

• Both pollutants and greenhouse gasses

come from fossil fuel combustion in power

generation activities

• Pollutants are managed through

abatement technology, greenhouse gas

technology in infancy – currently planned

to apply tax in South Africa from June

2019 – energy efficiency

• Particulate Matter

– Microscopic solids inhaled and stays in lungs; PM2.5 of greatest concern as this can reach

blood streams

• NOX

– Nitrogen oxides contain a group of pollutants, NO2 the greatest concern for human health

– Aggravates respiratory diseases – asthma; Addition with water vapor can cause acid rain –

nitric acid

• SOX

– Difficulty breathing; Gaseous SO2 harms trees and plants by decreasing growth potential

– Acid rain occurring with water vapour

• Mercury

– Kidney and central nervous systems gets affected most; Usually through food chain – e.g.

fish

POLLUTANTS – WHY WE CARE

South African limits International Trends

Particulate Matter 50mg/Nm3 <10mg/Nm3

Sulphur Dioxide 500mg/Nm3 <200mg/Nm3

Oxides of Nitrogen 750mg/Nm3 <150mg/Nm3

NB: This was taken in South African winter

TROPOSPHERIC MONITORING

National Environmental Management:Air Quality Act

(No 39 of 2004)

Priority AreaAir Quality

Management Plan

Ambient Air Quality Standards

Dust Fallout Management Regulations

MinimumEmissionStandards

Municipal By-laws

EmissionLicence

AIR QUALITY LEGISLATION IN SOUTH AFRICA

PRODUCTS OF COMBUSTION

• C + O2 = COX (CO2 and CO)

• S + O2 = SOX (SO2)

• N + O2 = NOX (N2O and NO2)

• Particulates

• Particulate Emissions– Fabric Filter Plants

– Electrostatic Precipitators

• SOX

– Wet Flue Gas Desulphurization applications

– Semi dry and dry applications to reduce water

• NOX

– Pre and post combustions applications

• Mercury– Form of which the mercury occurs important – oxidation required through

additional injection systems

• Multi-pollutant plants– Best suited technology is a circulating dry scrubber with FFP to reduce PM,

SOX and Mercury.

TECHNOLOGIES AVAILABLE

• Fabric Filter Plants

TECHNOLOGIES AVAILABLE

Pulse Jet

• The gas flows fromoutside the bags to theinside

• The bags are supported tothe tube plate at the topend

• Anti collapse cages

• Primary pulse andsecondary flow create ashock wave

• in-line or off-line cleaning

TECHNOLOGIES AVAILABLE

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dirty gas in

cleaned gas out

collecting plates

migration velocity

discharge electrode (-’ve)

corona field

• Electrostatic Precipitators

Improvements:Flue Gas Conditioning with NH3 and SO3

Higher Frequency Power SuppliesControl System UpgradesSystem Refurbishments

• SOX

– Pre-combustion limited to coal beneficiation and fuel switching

– During combustion sorbent injection (also CFB)

– Post combustion most favorable for legislated limits

– Is there a dry WGD for conventional coal?

TECHNOLOGIES AVAILABLE

Wet FGD• Fully saturates the flue gas with water.• Limestone or lime reagent.• Can produce commercial-grade gypsum

byproduct.• Higher capital cost / lower operating costs.• High relative water consumption• Water saving due to cooling possible

Semi-dry FGD• 20°C approach to saturation

temperature.• Lime reagent – product of limestone.• Disposal byproduct.• Lower capital cost / higher operating

costs. • Low relative water consumption

• NOX

– Thermal NOX vs Fuel NOX

– Pre-combustion limited to fuel switching

– During combustion characteristic of

• Combustion process (wall fired vs corner fired) and/or

• Firing systems– Conventional

– Staged combustion burners

– Post combustion SCR and SNCR

• Split NOX into diatomic nitrogen and water

• Temperature important

TECHNOLOGIES AVAILABLE

• Multipollutant– CFB FGD – Graf Wulff / Lurgi Process (Numerous suppliers) vs Wetted Solids

Absorbers (GE and Hitachi)

TECHNOLOGIES AVAILABLE

• Each technology has an effect on the overall power plant

• The use of modelling techniques and advance analysis

paramount to the correct technology application required

– with validation

• A stepwise approach is suggested to have a cost

effective solution achieved – specifically for PM in South

Africa

• Make owner part of solution finding – Understanding the

problem usually more complex than solutions.

INTEGRATED DESIGN

• Should it be gone with coal?

– South Africa is an island – energy management not fully

comparable to other countries

– Getting the mix right – IRP transparency

– Grid stability king – how do we manage emissions in an

changing environment – relative emissions vs point source

– Flexibility in grid – clean the emissions, make coal work better

CLOSING REMARKS

CLOSING REMARKSGERMANY DURING TYPICAL WINTER DAY – JANUARY 2019

CLOSING REMARKSGERMANY DURING TYPICAL SUMMER DAY – JUNE 2018

• Not easy or cost attractive road – However

environmental compliance does generate income

• The sooner the better – pressures on plants become

more relevant for production.

• Design for future requirements should be included

• Understanding technology for South Africa – using

international design know-how in context

• Project Development vs Project Specification

CLOSING REMARKS