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

2

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’

4

Air Pollution NOx Emissions

CO NOx

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)

T

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

Carbon Hydrogen Sulphur CO

Coal ~ CH

BTU/lb

14 000 61 000 4 000 4 400

Oil ~ CH2

y/2

H2O + heat

GJ/kg

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

Car

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

4.8 tCO2/yr

Kg/MWh

3

Air Pollution

2.5

Comparing Emissions from Thermal Energy Systems

SO2 NOx PM

2 1.5 1 0.5

“Cannot produce Air Pollution without making CO2”

0 Coal

Oil

Gas

GTCC

GTCHP

Bio

IGCC

1200 Kg/MWh

1000

• Natural Gas

800

• Coal and Oil

600

• Biomass and Syngas

400

‘Integrated analyses’

Carbon Dioxide

200 0 Coal

Oil

Gas

GTCC GTCHP

Bio

IGCC

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

(Kawasaki)

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

Alstom

Siemens

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 (mysolar.cat.com) 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

Lbs/HpHr

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

40

60

Overall Plant Thermal Efficiency %

80

100

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

ppm

(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

lb/MWhr

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

Size

3-20 MW 20-60 MW over 60

Alberta

CCME

(kg/MWhr)

(kg/MWhr)

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 ...)

(turbinetech.com)

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

use coal instead?

(KEMA)

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)

(Coen)

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

TCPL/EPCOR, Nipigon, ON

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)

32

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

Proper Thermal Sizing

HRSG Heat

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

CO2

To pipeline

Water O2

Coal Petcoke

Gasifier

CO

H2

Gas Cleanup

Water Shift Reaction

Slag

H2

Sulphur

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

MW

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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