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
---------
----
----------
--
---
-
-
-
+’ve
---------
----
--------- -
--
---
-
-
-
+’ve
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