Air Pollution and GHG Emissions

Air Pollution and GHG Emissions • Low NOx Emission Technologies for Gas Turbines • GHG Emissions Prevention • Canadian and International Emissions Sta...
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Air Pollution and GHG Emissions • Low NOx Emission Technologies for Gas Turbines • GHG Emissions Prevention • Canadian and International Emissions Standards • Clean Energy Systems - Balancing Objectives

TransCanada PipeLines RB211dle

General Electric LM2500 CHP Plant

Manfred Klein Coordinator, Energy & Environment Gas Turbine Labs, National Research Council 613-949-9686

[email protected]

Typical Industrial Gas Turbine Energy Systems • • • • • • •

Simple Cycle, Standby power New Gas Combined Cycle Combined Cycle Repowering Utility Coal Gasification Large Industrial Cogen Oilsands Gasification Pipeline Compression

• • • • •

Small Industrial Cogeneration Municipal District Energy Micro-T Distributed Power/Heat Waste Heat Recovery Process Off-Gases, Biofuels

About 24 000 MW in Canada


Air Emissions Air Pollution • • • • • • •

Sulphur Dioxide SO2 Nitrogen Oxides NO2 Volatile Organics VOC Fine Particulates PM Mercury & Heavy Metals Ammonia NH3 Carbon Monoxide CO

GHGs • • • •

Carbon Dioxide CO2 Methane CH4 Nitrous Oxide N20 SF6 et al

Ozone Depletion • CFCs Individual .. or …

System 3

What are Cleaner Energy Choices? Low Air Pollution, GHG Emissions, Air Toxics and Water Impacts

• Aggressive Energy Conservation and Efficiency • Small Renewable Energies, Biomass Fuels • High Efficiency Nat. Gas Systems (GTCHP, GTCC) • Large Hydro & Nuclear Facilities • Coal & Bitumen Gasification, Polygen w/CCS

New GT systems can lead to large GHG red’ns

• Energy Delivery; pipes & wires • Waste Energy Recovery

‘Clean Energy’ definition ? - Include thermal energy ?

IEA WEO ‘Blue Map’


Air Pollution NOx Emissions


O + N2 N + O2

NO + N NO + O

3 Compounds of Concern:

2000 K

NO, NO2 smog , N2O ghg Thermal NOx: High Temperature Combustion Fuel NOx: From N2 Content of Oil, Coal •

Nitrous Oxide is N2O, a GHG (Solar Turbines)


Fuel Combustion CxHy + (x + y/4) O2 = x CO2 + Energy Content

Carbon Hydrogen Sulphur CO

Coal ~ CH


14 000 61 000 4 000 4 400

Oil ~ CH2


H2O + heat


33 142 (LHV, 120) 9 10

Nat. Gas CH4

Simple CO2 Calculations - Energy (Heat RateHHV x CO2 factor) Coal Heavy Oil Natural Gas Gasoline

85-95 kg/GJ 74 kg/GJ 50 kg/GJ 68 kg/GJ ~ 2.4 kg/litre

Examples Coal Boiler

10 GJ/MWhr x 90 kgCO2/GJ


900 kgCO2/MWhr

Gas Cogen

6 GJ/MWhr x 50 kgCO2/GJ


300 kgCO2/MWhr


10 l /100km x 20000 km x 2.4 kg/l =

4.8 tCO2/yr



Air Pollution


Comparing Emissions from Thermal Energy Systems


2 1.5 1 0.5

“Cannot produce Air Pollution without making CO2”

0 Coal







1200 Kg/MWh


• Natural Gas


• Coal and Oil


• Biomass and Syngas


‘Integrated analyses’

Carbon Dioxide

200 0 Coal






Emissions in Gas Turbine Engines Factors Affecting NOx Emissions

• Unit efficiency ( AIR mass flow, Pressure Ratio, Turbine Inlet Temp) • Engine type (Aero or Frame) • Dry Low NOx combustor

• Full & Part load operation, starts • Cold and hot weather, humidity • Type of air compressor (spools) • N1/N2, Output Speeds • Specific Power (kW, per lb/sec air) • NOx Concentration vs Mass Flow

NOx Reduction Methods Steam/Water Injection • Prevention, 2/3 red‟n to 1 kg/MWhr • Some Combustion Component Wear • Plant Efficiency Penalty • Depends upon value of plant steam


Selective Catalytic Reduction (SCR) •

NH3 injection in HRSG catalyst, ~ 80% NOx Red‟n

• Backend Control - Ammonia emissions & handling (toxic), - fine PM, N2O ? - Cold Weather, Cycling duty - ammonia slip - Efficiency loss in HRSG - Full Fuel Cycle impact – Prod‟n, Delivery etc

IST Aecon

EA Assessments of Gas Turbine Plants (2002

Study, for TransCanada P/L and Environment Canada)

• Companies may be required to install added ammonia-based SCR controls after DLN • Ammonia transportation & handling is a serious local health and safety issue • Given the capital & operating costs and collateral impacts associated with SCR systems, the environmental benefits do not justify the economic expense. (T. McCann, B. Howard, M. Klein)

Marginal, low $/tonne benefit after DLN

Dry Low Emissions Combustion • Preventative reduction by 60-90% • Maintains High Efficiency

• Good experience with large industrial units • Some Reliability Issues for Aeroderivatives • Too Low Values may lead to inoperability and combustor problems • How important are CO emissions? • Effects of Plant Cycling

• Applied to Syngas combustion ?

Solar SoLoNox

Dry Low NOx on Large GT Units

Annular EV burner

GE Frame 7F, DLN2



DLN Systems for GE Heavy Duty Gas Turbines

Aero-Derived DLN Systems

GE LM6000 DLE Triple Annular Dome

Air flow Air gas mixture Combustion products Cooling air

Rolls Royce Canada

Rolls Royce Canada RB211 DLE

Gas Turbine Emission Guidelines & Standards Objectives • Prevention of Air Pollution,Toxics • Minimize GHGs • Energy Conservation • System Efficiency • Size and Location • Minimize Water Impacts • Noise

• Reduce CFCs • Energy Security • Emissions Trading

NOVA Chemicals, Joffre AB

Look for solutions with; Multiple Economic Benefits, Systems Analysis Balanced Approach

Clean Energy Balancing Act Energy Supply Choices

Energy Security

Global Atmosphere Climate & Ozone Layer

Conservation & Efficiency

Emissions Trading

Policy, Regulations, Technology

Demand & Consumption System Reliability

Economic Performance 17

Examples of International Standards – 2005 (for GT Units Larger than ~ 10 MWe, gas fuel)

United States United Kingdom Germany France Japan Canada Australia EU LCPD World Bank • •

2 - 42 ppm 60 mg/m3 75 mg/m3 50 mg/m3 * 15 - 70 ppm 140 g/GJout * 70 mg/m3 50 - 75 mg/m3 * 125 mg/m3

Facility Cogeneration Incentives (Values Subject to Change) Uncontrolled NOx levls were 100-300 ppm (200-600 mg/m3 )

Sample Emissions Unit Conversions for NOx Percent O2 conversions for ppmv • from 25 ppmv at 15% O2 to value for 16% O2 = 21 ppmv 3% O2 = 76 ppmv

NOx ppmv to mg/Nm3 with the same % O2 basis • from 50 mg/m3 = 24 ppmv

Natural Gas at 15% O2 (LHV Basis, fuel input)

• 25 ppmv NOx = 0.099 lb/MMBTU (= 42.9 g/GJ) 1 lbNOx/MMBTU = 252 ppmv

Diesel fuel at 15% O2 (LHV Basis, fuel input) 25 ppmv NOx = 0.10 lb/MMBTU (= 43.5 g/GJ)

From Solar Turbines ( See “Customer Support” Toolbox

Gas Turbine Emissions Criteria Traditional concentration (ppm, mg/m3) and fuel input (g/Gjin , lb/MMBTU) criteria; • • • •

difficult to interpret do not give appropriate design signal do not encourage system efficiency do not encourage Pollution Prevention

• Aviation uses ‘LTO’ Operations Cycle • Recip engines have kg/MWhr rules

ICAO - aircraft (kgNOx/thrust)

Output-based Rules; Mass per Product Output (kg/tonne, kg/MWhr, g/GJout ) tonnes/yr $/tonne $/MWhr


Canadian GT Emission Guidelines (1992) • Guideline Reflects National Consensus • Balanced NOx Prevention Technology • Regulatory Certainty • Output-Based Standard for Efficiency (140 g/GJout Power + 40 g/GJ Heat) • • • • • • •

Engine Sizing Considerations Promotes Cogeneration and low CO2 Peaking units ( 20 MWe

10 20



Overall Plant Thermal Efficiency %



New US EPA Rules for Gas Turbines Can choose Output-based, or Concentration-Based Rules (EPA OAR-2004-0490) Size, Heat Input (MMBTU/hr)


(New Units, Natural Gas Fuel) < 50 (electricity, 3.5 MWe) (mechanical, 3.5 MW) 50 to 850 (3 – 110 MW) Over 850 (> 110 MW)

42 100 25 15

2.3 5.5 1.2 0.43

Units in Arctic, Offshore < 30 MW > 30 MW

150 96

8.7 4.7

• MW could include MWth for waste heat in CHP • Efficiency based, SCR likely not required • Flexible Emissions Monitoring


Alberta Environment NOx Emission Guidelines (Gas Turbines for Electricity Generation, 2005)


3-20 MW 20-60 MW over 60





0.6 0.4 0.3

0.86 0.5 0.5


MWhr includes power and thermal energy.


Alberta levels were developed through CASA in 2004 as a modest reduction from national CCME levels, also taking into account the needs of larger units over 60 MW in size.

Gas Turbine Operability in Cold Climates • How well does DLN operation adjust to very cold ambients ? (-30 to - 50oC) • How can unit power & efficiency be optimized during cold weather ? • Acoustic Oscillations, noise

TCPL Northern Ontario

• How important are CO emissions? • Remote O&M capabilities • Can an Output-based GT design contribute to solutions?

Rolls Royce RB211dle

Stittsville ON (MK)

Combustor Dynamics “Humming” Acoustic Oscillations Under Transient Conditions, caused by; • Ultra-Low NOx ppm Design • CO and turndown req‟ts • Cyclic GT Unit Loading • Ambient Temp, Pressure Ratio, Fuel properties (Nat Gas, LNG, Syngas ...)


1. Natural Frequencies and Resonance 2. Vibration, Trips & Shutdown 3. „Zero‟ GT emissions

use coal instead?


Waste Heat and Duct Burners in CHP • Duct Burners for auxiliary firing can double/triple steam output from HRSG ~100 % efficiency for heat) • Duct burners can add a bit of combustion NOx, … but they allow a smaller size of GT engine for given heat load (reduces annual fuel & emissions) • Also increases heat transfer, lowers stack temp • HRSG naturally silences GT exhaust noise IST

Heat : Power ratio (Solar Turbines)


Duct Firing Creates a higher Heat:Power ratio which can enhance system efficiency and plant operating flexibility. To meet periodic high steam demands; - Lowers stack exhaust temperature, improving heat recovery and efficiency

C. Meyer-Homji, Bechtel Corp.

Allows for a smaller Gas Turbine engine choice, or avoids an additional Boiler

Are there PM2.5 particulate emissions from gas-fired turbines? (AP42 - 0.07 lb/MWhr ?)


2 million t/yr Air

Air Filter 99.8%

60 kT/yr fuel

Does dry NG combustion produce fine PM emissions? What is the Inlet-Exhaust mass balance ?

Are there any Air Toxics ?

Emissions Measurement • Compliance and Emission Inventories • Emissions Trading - NOx, SO2, CO2 • • • •

Continuous Emissions Measurement Process Estimation Methods Surrogate & parametric methods Predictive Emissions Monitoring

CEM Specialties

PEMs; • • • •

good predictability of GT operation cost-effective emissions reporting process efficiency optimization a good solution for DLN facilities

Emissions Averaging Time is Important Env Can CEM van at TCPL, ON

Env‟tl Solutions for Gas Pipeline Compression • Efficient and Reliable Gas Turbine, with DLN Combustion

• Minimizing Stops and Starts • Waste Heat Recovery • Gas-to-Gas Exchange, Aerial Coolers • Dry Gas Seals to reduce methane leakage, and reduced Venting

Gas Compressor Dry Gas Seals

• Air or Hydraulic Engine Starters • System Optimization

Aerial coolers


Critical Elements for CHP Systems Producing 2-3 forms of energy from the same fuel, in same process. •

Awareness of Opportunities

Nearby Site

Plant Sizing to Match Thermal Load

Seasonal Heat/Cooling Design

Electrical Utility Interconnection

Availability of Gas, Bio, H2 fuels

Low Air Pollution, Local Impacts

Greenhouse Gases & Allocation

Output-based Emission Rules

Energy Quality (Exergy)


Gas Turbine Emission Prevention & Control (NOx, GHGs) CEM or PEM

Proper Thermal Sizing


HEPA filter Duct Firing

Steam or N2 injection

Selective Catalytic Reduction ? CH4 Leakage Prevention Maximizing System Output CHP Efficiency

Dry Low NOx Combustion

H2 , Syngas Fuels

System Reliability GE Power Systems33

Env’tl Assessment of Mackenzie Gas Pipeline (2004-06) 95% of GHG & NOx emissions are from gas turbine units and small gensets - 20 gas turbines (270 MW) - 10 small recip engines (13 MW) • NOx combustion levels which are too low will cause engine instability. • CCME Guideline balances NOx prevention to moderate level, with low GHGs • Cold weather, O&M considerations BAT = • Dry Low NOx, Waste Heat Recovery • BMPs for fugitive, vented methane • Maintain system reliability

(Imperial Oil)

Solid Fuel Gasification System Air N2

Air separation


To pipeline

Water O2

Coal Petcoke




Gas Cleanup

Water Shift Reaction




Difficult Dry Low NOx solution - need dilution from N2 Is very low ppm NOx necessary, or even possible ?

Is this a gas plant, or a coal plant?

Gas Turbine Combined Cycle


Process Heat

N2 Injection

Fuel Flexibility - Combustion Characteristics of SynGas Fuels Hydrogen • High Volume and Heat Value • High Flame Temp. • High Flame speed

• Flashback, auto-ignition • Higher NOx ? (Hannemann et al, Siemens)

Carbon Monoxide • High Flame Temp. • High Density • Low flame speed • Toxicity

(Solar Turbines)

Some Issues for Consideration … Gas Turbine is an Engine (hot pressurized air for Power & Heat) How can various types of Air Emissions be managed effectively ? What is the ‘right’ level of NOx emissions from a reliable system? Can ‘output-based’ design improve performance over a ‘ppmv’ design? How do we deal with off-design, cold weather & cycling conditions ? What does BAT or BACT mean ? Can CAP-ex choices be made consistent with OP-ex choices ? How can CAC and GHG emissions be reported effectively ?

Concluding Remarks • Gas Turbine & CHP systems represent key solutions • Best Available Technology: Waste Heat Recovery, DLN, Gasification • Cogeneration: HEAT POWER • Emissions: Air Pollution

Carbon Dioxide

• Fuel flexibility & Gasification are important GT challenges • Need ‘System Integration’ , Balancing of Issues • Need Collaborative R&D and Knowledge TCPL Ottawa

GTAA Pearson

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