Impact of quality and quantity of fuel on achieving PAT targets
“Implementation of PAT Scheme in Thermal Power Stations – Issues and Challenges”
30.1.2015 India Habitat Centre, Lodhi Road, New Delhi
Dr. W.A.Benesch Director Energy Technolgies
Dr. Benesch 30.1.2015
PAT and power industry
• India’s PAT (Perform, Achieve, Trade) scheme provides a model to increase economic benefits with climate co-benefits
• The PAT scheme targets energy consumption reductions of 6.6 Mio t of oil equivalent in 478 covered facilities
• Plant specific targets are set instead of a sectorial target • The average reduction target is 4.8% • Power sector plays a dominant role
WE are STEAG. Our facts and figures
• WE are specialists in the generation of electricity and heat on the basis of a wide variety of technologies, and for the marketing of electricity and heat;
• with 9 hard coal fired and 2 refinery power plants in Germany, and 3 hard coal fired power plants in Colombia, Turkey and the Philippines;
• with more than 200 distributed generating facilities on the basis of renewable sources, for energy supply to industry and heat supply;
• with an installed capacity of 8,500 MW in Germany and 1,700 MW abroad;
• with a workforce of 3,700 in Germany and 2,300 abroad;
• with total sales of EUR 2.9 billion and EBITDA of EUR 366 million in 2013;
• with an investment volume of around EUR 363 million in 2013.
Dr.Benesch 30.1.2015
We do not have a PAT scheme in Germany but….
….. according to the rules of our electricity market we have to follow the merit order.
This means Highest efficiency and Lowest fuel price
And here we are connected to PAT Dr.Benesch 30.1.2015
Steag optimization experience with own power stations for more than 75 years
Bergkamen A 780 MW
Bergkamen Herne
Herne 2/3/4 960 MW
Bexbach Duisburg-Walsum
Iskenderun
Iskenderun 1/2 1,320 MW
Bexbach 1 780 MW Walsum 7/9/10 1350MW
Voerde A/B 1,522 MW West 1/2 712 MW Weiher 3 724 MW
Weiher Voerde
Mindanao Lünen Völklingen-Fenne Paipa
Lünen 6/7 507 MW Mindanao 1/2 232 MW Termopaipa IV 165 MW MKV, HKV, MHK *) 466 MW
Dr.Benesch 30.1.2015
Dr. Benesch 30.1.2015
How is coal affected by PAT?
PAT sets targets for improvements in energy efficiency in thermal power plants. At least efficiency of power plants is monitored and should be improved by this tool. How is coal now affected? • Coal quantity is an indicator for
efficiency
• Coal quality is essential for efficiency
Dr. Benesch 30.1.2015
Some issues
• With high grade coal of cause higher efficiencies could be reached easier, but what to do if these coals are not available?
• The PAT scheme sets plant specific targets. If the achieved efficiency of a power station should be benchmarked -the question could be raised- how far is the coal quality influencing this comparison?
• Main influencing parameters are ash, water and sulfur content, but to what extend?
• Coal quality is heavily influencing slagging and fouling which itself influences boiler efficiency.
• Combustion efficiency is governed by volatile matter content but also by the boiler design.
• Design coal and operating coal show very often great differences. Accordingly the design efficiency and the reached efficiency in day to day operation are different.
• Coal washing can influence quality, uniformity and quantity of fuel.
Mixed and unmixed coals?
When examining coal analyses, it has to be taken into consideration that one hardly ever has to do with one individual coal.
Even in case of coal from one mining area, the power station is frequently supplied with mixed sorts of coal from different coal pits or, if they come from one pit, from different seems.
Mixed sorts of coal as to their grinding and combustion qualities are basically different from one unmixed coal.
So it becomes very important to discuss the possibilities and restrictions of coal mixing.
Dr.Benesch 30.1.2015
Dr. Benesch 30.1.2015
What is poor coal
• High ash content
• Hardness
• High water content
• High sulfur content
• Non-uniform quality
Dr. Benesch 30.1.2015
Implications of poor coal quality
• Emissions environment
• Wear costs, availability
• Maintanance costs
• El. consumption PAT related
• Boiler efficiency PAT related
• Slagging and fouling PAT related
• Less power output overall capacity
Dr. Benesch 30.1.2015
How to achieve a benefit in the PAT scheme fuel related
• Control coal quality
• If possible buy an appropriate coal
• Consider washed coal
• Homogenize
Definitions dealing with mixing of coal
Homogenization Minimize fluctuations in coal properties Mixing Definite new coal qualities, but some elements of the original coals can still be detected Blending Definite new coal qualities
Quality of the process
In day to day operation with the existing equipment at the power stations, a homogenization other than a mixing or blending is usually possible.
Dr.Benesch 30.1.2015
Dr. Benesch 30.1.2015
Indirect effects of efficiency increase
Higher capacity Cost reduction Environmental friendliness
Dr. Benesch 30.1.2015
FGD / DENOX
Fuel gas condition:: - CO 2
- temperature
Steam parameters : - pressure - temperature
Reheater spray attemperator: - flow rate
Parasitic power consumption - auxiliaries load - exciter - equipment
firing: - O 2
- CO - after burning - leakage - NO X
Fuel - mass flow - Quality
Feedwater- preheating: - terminal temperature difference
condenser - terminal temperature difference - temperature
- boiler inlet temperature
Performance monitoring of power stations as part of the PAT scheme Online
Dr. Benesch 30.1.2015
Performance monitoring of power stations as part of the PAT scheme Offline with Mobile Measuring Vehicle
• Pulverized-coal measuring module • Fly ash measuring module • PC / fly ash analysing module
• Extensive gas analyzing module • Portable gas analyzing module • Calibration module for gas analyzers
• Temperature measuring module • Volume flow rates measuring
module • Measuring module for turbines
• Measuring module for pumps • Measuring module for condensers • Measuring-value data logging and
processing module
Performance monitoring of power stations as part of the PAT scheme Efficiency team
Formation of an “energy efficiency team” (3 to 4 people) Plant visits (2 weeks on site) document review and
discussions with the station personnel Creation of a database collecting the key information for the
regarded power station Check of the current coal quality and comparison with the
design coal Comparison of as built and theoretical boiler performance
based on acceptance tests Check of every load case of the boiler and the current
efficiency of the boiler Evaluation of the heat absorption in the different boiler parts
and the air preheater Monitoring of the auxiliary power consumption, the air
ingress, the milling system and the soot blowing system Evaluation of the turbine condition, main components of the
water steam cycle, the whole cold end and the related heat rate
Dr.Benesch 30.1.2015
Dr. Benesch 30.1.2015
Coal quality influencing the entire power plant
Grain sizeBulk densitySpecific weightGrindabilityWear characteristicPyrite contentSulphur contentSand contentWood contentSalt contentHeating valuesElementary analysisVolatile mattersWater contentAsh contentIgnition temperatureCompositionViscosityMelting qualityCementabilityWater contentAngle of slope
FuelParameters Coal
handlingCoalmills
Dust firingsystem
Steamgenerator
Ashhandling
Airpreheater
FDF IDF ESP FGD
Ash
Components
Coal
Availability and maintenance costs are governed by the parts being in contact with the coal - efficiency is part of the game -
Dr. Benesch 30.1.2015
Improper coal and influence on combustion system and boiler
• Bad or too late ignition
• Too early ignition
• Too long flames (touching the walls)
• Too high CO or NOx formation
• Wall corrosion
• Fouling problems
• Problems with bottom ash
• Limitation of part load and full load
Dr. Benesch 30.1.2015
Chlorine content of coals and influence on corrosion
Rel
ativ
e co
rros
ion
rate
Chlorine content in % (ar)
country
GB USA Australia Belgium India New Zeeland Poland South Africa
Chlorine content in % (ar)
Dr. Benesch 30.1.2015
Slagging and Fouling
• current coal • coal mixture • coal history • appropriate boiler design
Dr. Benesch 30.1.2015
Example for unburnt carbon in filter ash for high grade coals depending on volatile matter content
0 5 1 0 1 5 2 0 2 5 3 0 3 50
5
1 0
1 5
2 0
2 5
Volatile matter content in % (waf)
Unb
urnt
car
bon
in a
sh in
%
Dr. Benesch 30.1.2015
"Treatment of new coal"
Offered Coal- Origin- Quantity
Special Conditions
- Spotmarket- Special fuel
Additional Test and Information- Theoretical- Laboritory- Fullscale test incinerations
BlendedUnblended
Known Quality
Data from- Coal data bank- Standard analysis
Check whether insideof range
of a STEAG power station(- Technical criteria)
Economical
TechnicalDecision
Blendedinsiderange
Incineration
Definition of aBlend
YesNoYes
No
Yes
No
Yes
RejectedNo
Rejected
No
Yes
Yes
No
Combustion
Coal washing can influence quality, uniformity and quantity of fuel
Advantages • Efficiency increase
• Reduced land consumption
• Saved transport capacity
• lower transportation costs
• less investment for boiler, fuel- and ash- handling
• lower maintenance costs due to lower erosion
Disadvantages • Investment in coal
washing plant
• operation costs
Dr.Benesch 30.1.2015
Coal washing yes or no
⇒ Typically coal washing is more economic than transportation and combustion of low grade coals
0
20
40
60
80
100
120
coalwashing
minemouth
100km 5000km
transportationoperating costsinvestment
0
20
40
60
80
100
120
coalwashing
minemouth
100km 5000km
transportationoperating costsinvestment
∆ ash 5% ∆ ash 20%
Dr.Benesch 30.1.2015
Benchmarking needs
• PAT is asking for high efficiency
• Coal quality is a major factor influencing efficiency
• Examples had been given how poor coal reduces efficiency
• Appropriate coal has to be chosen if possible
• Efficiency loss due to poor coal quality has always cost increase as a result
• If PAT should be successful the influencing parameters have to be made transparent
⇒ At least apples should not be compared with pears
Dr.Benesch 30.1.2015
Power generating cost
Operation Operation
Capital
Administration
Power generating cost
Administration
Capital
Energy Energy
•Pay level •Working hours •Regulatory requirements
•Unit number •Output •Operation mode •Coal type
•Organization •Workflows •External service material •Technology
Site Power plant type/ "Comparative use Gap“
Adjustments Power Plant 1 Power Plant 2
Benchmarking Example for necessary adjustments
Dr.Benesch 30.1.2015
Summary
Coal quality is influencing efficiency values
Typically coal quality can only be influenced limited
• Coal washing and
• Homogenization are of help
Proper benchmarking of heat consumption needs consideration of coal quality and quantity
Differences between design and really operated coal have to be considered
Choosing a certain coal quality many parts of the power plant are affected, technical and commercial aspects are heavily linked.
Every coal is black But not every black is coal
Dr.Benesch 30.1.2015