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Modernizationof Combustion Systems
2
Contents
Modernization of Combustion Systems 3
Key for a Successful Rehabilitation Project 4
Competence in Firing Systems 8
Our Own Manufacturing Facilities 9
Success Products 10
Solutions to Increasing Plant Flexibility 18
Rehabilitations – References 20
Stronger together
The merger of the “thermal power plant” fields of Mitsubishi Heavy Industries, Ltd., (MHI)
and Hitachi, Ltd., has brought about Mitsubishi Hitachi Power Systems, Ltd., (MHPS) – one of
the world’s largest companies in thermal power generation systems.
An important mainstay of this corporate group is Mitsubishi Hitachi Power Systems Europe
GmbH (MHPSE), the successor to Hitachi Power Europe GmbH. The energy plant con
structor (based in Duisburg) looks back over a +100year track record in planning and
constructing fossilfired power plants. MHPSE constructs turnkey plants, supplies key
components (e. g. utility steam generators, environmental engineering equipment, turbines,
burners, grinding systems) and handles service and rehabilitation.
Stakeholders in Mitsubishi Hitachi Power Systems Europe GmbH
MHPSE
MHPS
MHI Hitachi, Ltd.
65% 35%
100%
Mitsubishi Hitachi Power Systems Europe GmbH
Babcock Fertigungszentrum GmbH
Production of first-class components for power plants (e. g. coal mill), mainly for MHPSE
MHPS Africa (Pty) Ltd. Subsidiary of MHPSE in South Africa
Meeraner Dampfkesselbau GmbHManufacturing of premium components for utility steam generators (e. g. pressure parts) for power plants
Donges Steel Tec GmbHOne of Germany’s leading steel and bridge constructors; manufacturing of steel structures for power plants
MH Power Systems Europe Service GmbHService, rehabilitation and components in the industrial plant field
SUBSIDIARIES AND RELATED COMPANIES
Mitsubishi Hitachi Power Systems Europe
Modernization of Combustion Systems 3
Low Emission and Flexibility Issues
Present developments on the energy market are enlarging the wide portfolio of modernization
schemes by flexibility issues as, in the future, conventional power plants will be facing
competition for power production during those limited and fluctuating time cycles caused by
increased production from renewable energies.
Modernization measures usually comprise
■■ Increase of availability, efficiency and performance
■■ Optimization of combustion process, reduction of emissions
■■ Lifetime extensions
This is extended nowadays by flexibility issues like
■■ Load ramp enhancement
■■ Startup / low load optimization
■■ Fuel alternatives (fuel change, biomass, predried pulverized fuel, skip of oil / gas)
■■ Pulverized fuel storage
Complex measures are required to operate existing units economically under these new
market conditions. Here modernization of the firing system plays a key role. MHPSE, as a
modern technology supplier with many years of competence in the worldwide newbuilt
and rehabilitation business, is on hand both for classic rehabilitation and the new tasks.
* See also MHPSE brochure: Solid Fuel Firing Systems and Components
in combination with a wealth of experience with other components like fans, air heaters, soot blowers and pumps from ongoing contracts
Combustion solu-tions using MHPSE’s innovative swirl burner technology for all fuels
Milling technology (lignite, bituminous coal)
Coal feeder and deashing technology
Pressure parts, ductworks
For all modernization work involving the combustion process, MHPSE delivers – based on its own technology
and key components * – the required advanced
Modernization of Combustion Systems
4
Own Engineering and Technology
Within the last 30 years MHPSE has gained experience from more than 550 modernization
schemes, rehabilitation work and studies worldwide and thus MHPSE is your partner for
challenging rehabilitation undertakings for the entire boiler.
MHPSE’s primary interest is the engineering driven concept of design for best solutions as
well as supplying its own key components – with labor intensive manufacturing as well
as dismantling / erection work to be executed by local partners (advised / supervised by
MHPSE specialists) or by power plant staff.
MHPSE offers advantages in technology and competence for your project
■■ Experienced acknowledged specialists and contact partners
■■ Own product development (patents), own software development –
partly in company wide cooperation
■■ Active participation (project leader) in essential research activities
■■ Parametric design, supported by uptodate tools (PDS, ProE)
■■ Accredited own laboratory for coal, ash and damage analysis
■■ Experience gained from worldwide commissioning and operation of ongoing plants
■■ CFD simulation (Computational Fluid Dynamic calculations) to support design concepts
Overall Rehabilitation Performance Increase 42%
Upgrade of Combustion System NOX Reduction 19%
Increase of Efficiency 19% and Availability
Redesign of Firing System 10% Fuel Change
Lifetime Extension / 10% Others
Key for a Successful Rehabilitation Project
Modernization of Combustion Systems 5
Cooperative Approach
We are your partner for complex rehabilitation work in which – through process optimization
of plants and components – remarkable economic and ecological improvements are gained.
This can even come from a simple design solution supported by CFD simulation calculations.
MHPSE has already designed the most effective of concepts in instances of where the OEM’s
solutions have failed.
Upfront of a potential rehabilitation MHPSE offers engineering concepts for a common
stepwise approach:
The benefits
■■ MHPSE’s proven cost and time efficient way of proceeding for identification of
potential measures
■■ Development of effective measures for complete rehabilitation to schedule
■■ Risk limitation due to solutions supported by Simulation Calculations (CFD)
Should you be interested, we are more than ready to discuss these steps in detail with you.
Time and Budget Saving Procedure for a Solution Demonstration
Your detailed plant / component expertise including knowledge about damage and malfunctions as well as your draft ideas for improvement.
Our experts’ knowledge about solutions and expe-rience obtained in similar applications worldwide. *
* Example: Similar grinding / firing topics in the Balkans and Australia
+ Bundled “hand in hand” knowledge as best basis for the project, from the first idea up to successful completion.
==
Detailed Study
Common Investigation for Problem Analysis
Basis of the Ultimate Solution
MHPSE REVIEW of plant data
EXPERIENCE EXCHANGE with plant staff
SITE INVESTIGATION Mill measurement program and coal /ash analysis by MHPSE
UPGRADE CONCEPT (BY MHPSE) supported by CFD simulation with budget indication
UPGRADE OF PILOT EQUIPMENT for demonstration purposes
6
CFD Simulation Calculations
CFD programs can be applied by many users. However without validation by reality and
associated calibration, the results may not serve as a reliable design support.
For MHPSE these programs are essential as valuable tools in supporting concept develop
ments. For this reason, MHPSE is very much interested in permanently calibrating those
programs for simulation of fluid dynamics and emissions from its own knowhow and latest
MHPSE supplier experience. The aim of this validation is to have a reliable tool during the
design stage to simulate the reality for even complex issues.
By application of these calibrated CFD programs, verification is undertaken of MHPSE’s
engineered solution for optimization of the components or complete plants.
■■ Own test facilities
■■ Intensive research and
development activities
■■ MHPSE’s own laboratory
(accredited DIN EN ISO / IEC 17025)
■■ MHPSE’s own commissioning
experts / activities
■■ Testing of research findings
in utility plants
■■ Operation experience from
utility plants
■■ Many years of knowhow
■■ Internal (GermanJapan) experience
exchange for continuous
optimization and development of
the latest calculation methods
Feedback from Reality
Key for a Successful Rehabilitation Project
Modernization of Combustion Systems 7
Visualization of Improvements
Thus for potential rehabilitation purposes, both the existing situation with related problems as
well as the future situation can be demonstrated after implementation of MHPSE’s concept
from an impressive visual comparison – this is done during the early stage without
affecting the plant – and under reasonable costs.
Latest Developments
Meanwhile the development of the simulation programs has been extended with the result that
■■ Dynamics of ignition and combustion process at burners as well as
■■ Location and rate of wear, e. g. in PF ducts
can be impressively simulated; the latter being an important forecasting element for the service
and maintenance department.
This procedure from CFD simulation support has proven to be successful. Based on key
boiler data and parameters, coal / ash analysis as well as information about malfunction,
studies enable MHPSE to evaluate the intended rehabilitation measures.
In line with the given project task, MHPSE defines the required scope of measures and related
guarantee values and evaluates budget requirements.
Existing Situation MHPSE Upgrade Concept
Same task for similar mills (Serbia /Australia)
8
Main Driver for Plant Improvement
Process optimization of the combustion process together with the most advanced grinding
and firing equipment allow MHPSE to offer efficient rehabilitation work at reasonable costs.
Solutions for burners, grinding equipment as well as the furnace – which have been refined
for over 10 years now – are optimized using the above simulation calculations. Typical firing
problems which can lead to inefficient operations, unnecessary emissions or even plant
damage are the following:
■■ Unstable coal firing
■■ Support firing
■■ Overhigh emissions (NOX, CO)
■■ Problems with fuel changeovers
■■ Incomplete combustion (high UBC values)
■■ Overhigh furnace end temperature (FEGT)
■■ Slagging / fouling problems
■■ Furnace wall corrosion
As a rule, in order to reach optimization targets on a sustainable basis, all related systems like
grinding equipment, burners and the furnace need to be considered as a whole. Optimized
grinding is the key to successful firing rehabilitation. Related mill measurements on existing
plants provide valuable information on the optimization potential. Improved grinding perfor
mance in combination with MHPSE’s modern burner generation represent proven solutions
for sustainable boiler modernization. However, for successful low NOX firing rehabilitation,
infiltrated air needs to be reduced – it should not exceed 15 % (lignite) or 5 % (bituminous coal)
at furnace exit. Therefore, seal tightness issues also need to be considered – something
which is also beneficial for economic plant operation.
Not only mills and burners
In connection with a rehabilitation of the firing
equipment, MHPSE also analyses the im
pact of changes in boiler heat transfer due to
combustion air reduction – as it is the case
with most low NOX rehabilitations (see also
typical sketch for a revamp with RS® Burn
ers). Given obvious variations, we would
propose measures to secure the original
steam parameters either at the turbine entry
or at the district heating extraction system.
Existing: Jet Burner λ = 1.29 no OFA
New: RS® Burner λ = 1.18 with OFA
Boile
r Hei
ght/
Flue
Gas
Pat
h
Flue Gas Temperature
BurnerZone
Furnace Exit
Typical
➔ Over Fire Air
Low NOX Rehabilitation: Temperature Profiles
Competence in Firing Systems
Modernization of Combustion Systems 9
Maximum Quality
In contrast to most other solution provider, Mitsubishi Hitachi Power Systems Europe can
utilize its own manufacturing.
This includes pressure parts for utility steam generators and headers (at “Meeraner Dampf
kesselbau GmbH”), coal mills and burners (“Babcock Fertigungszentrum GmbH”), material
handling systems and steel structures (“Donges SteelTec GmbH”). As a result, MHPSE is not
primarily tied to subcontractors and creates a true “Alliance for Quality”.
Maximum quality is needed in power plant engineering particularly since components are
subject to considerable stresses and must dependably perform their functions for decades
under continuous operations. That is why MHPSE’s subsidiaries have established special
priorities in controlling production quality. Thanks to constant refinements in hightech materials
involving, for instance, special alloys for pressure parts, components can be used even more
economically and in a more environmentally compatible manner. Based on this experience and
depending on the project prerequisites, cooperation with local partners is also an option.
Our Own Manufacturing Facilities
10
The Grinding System – Key Component with Huge Refurbishment Potential
Optimized grinding in terms of throughput and grinding fineness and by in parallel
minimization of wear is the goal of mill rehabilitations. Even without any firing upgrades,
MHPSE has attained remarkable plant improvements which, in the main, have impacted
positively on boiler operation efficiencies.
As a specialist for mills with its own technology, MHPSE possesses enormous competence
in all kinds of mills and coals for new installations and upgrades – the latter also for
“Non OEM” mills. MHPSE’s comprehensive knowledge on grinding and fluid dynamics within
the mills / classifiers and their optimization potential allows the company to improve matters
through simple design measures backed up by CFD simulation.
DGS® Mills, NV Mills, N Mills for Lignite
The main challenge behind a lignite mill upgrade is to optimize the contradictory targets of fuel
throughput and grinding fineness in such a way that the increase of fuel throughput – mostly
in connection with improved grinding fineness – can be obtained by a minimum of wear with
consideration given to the permitted conditions (temperature, oxygen content).
Performance can often be improved remarkably without the need to invest in any increase of
fan wheel speed or fan wheel diameter – something usually requiring either an upgrade or
replacement of, for instance, the wheel itself, shafts, bearings, drive and coupling.
Efficient constructive measures either in the preheater section (for DGS® mills), classifier
(NV, N mills) or in the mill housing are MHPSE’s specialty for tapping the full potential of the
mill – again supported by cfd simulation.
Exemplary for MHPSE’s competence is the upgrade in Weisweiler PP at fan mill
N80.75. Instead of the requested contractual throughput increase of almost 10 %,
the reasonable measures which MHPSE took resulted in a 40 % increase
Success Products
Modernization of Combustion Systems 11
MPS® Mills for Bituminous Coal
The performance of vertical spindle mills depends on the geometric dimensions, revolution
speed of the grinding table and the grinding force itself.
As a prerequisite for these mill upgrades it needs to be ensured that sufficient delivery air is
available and that the mill primary air pressure as well as mill drive power have the required
margins. This necessitates also investigating the mill motor, PA fans and pfpiping in detail.
Application of the above measures for variable adjustment of dust fineness during operation
also secures higher flexibility during load changes and a temporary increase of pulverized fuel
outlet capacity.
MPS® MillMeasures for increasing grinding capacity:
■ Conversion of existing gearbox or replacement by new gearbox to increase the mill table speed
■ Implementation of an adjustable hydraulic grinding force system
■ Increase of maximal grinding forces by reinforcement of bearings, drives, tension frame, tension rod, hydraulic system, etc.
■ Optimization and new design of grinding rollers and grinding segments
with the latter two being complex solutions securing capacity increases of up to 60 %
Measures for improved grinding fineness (steeper distribution curve):
■ Replacement with new dynamic classifiers, often in existing classifier house
■ Classifier drive equipped with frequency inverters
Both comparatively simple conversions which by maintaining pulverized fuel fineness increase mill throughput by up to 10 %
U.S. Standard Sieve
Particle Size in µm
V6
Pass
ing
(%)
Resi
due
R (%
)
400
63 90 20050 70 150 300 70050030
270 200 100 70 50 30
50
40
30
20
10
1.0
0.1
0.01
60
50.00
60.00
70.00
80.00
90.00
99.00
99.90
99.99
40.00140
V3 V1 V5
0 rpm
110
rpm
100
rpm
85 rp
m
SLS Classifier – latest classifier design
12
Stateoftheart Combustion with Proven Burners from MHPSE
MHPSE’s ongoing burner fleet covers the whole fuel range for thermal applications
■■ For all fossil fuels – from anthracite via bituminous and subbituminous coal up to lignite,
including predried lignite as well as different kinds of oil and gas qualities
■■ For many biomass applications and their dried or torrefied variants
All burners are based on the same design philosophy, which derives from MHPSE experts’
knowledge and detailed understanding about the ignition and combustion process.
Full combustion control
MHPSE’s burners are characterized by excellent ignition thus ensuring controlled combustion
over a wide range together with high flame stability and low emission values. Due to their
features the burners can cope admirably with high fuel flexibility. Firing systems designed
for problematical coals can be significantly simplified. MHPSE’s burners are designed for
stoichiometric conditions. This impacts positively on the fouling and slagging behavior – even
with the properties of problematical fuels – and optimally protects the furnace walls against
corrosive flue gas products.
The principle of staged burner design is focused on fuel treatment to prepare the particles for
pyrolysis and ignition under the required conditions. The characteristic features are expressed
by the definition of initiation and course of ignition – with the latter meeting the equation:
IGNITION = PYROLYSIS + OXIDATION
MHPSE Burner Fleet
Lignite / Brown Coal
Sub Bituminous
Bituminous Anthracite Biomass (co-firing)
Biomass (stand-alone)
Oil / Gas
BFG Turn down ratio (Control range)
Burner Size MWth
pf dried pf dried pf dried pf dried pf dried pf dried
DS® X X X X X 1 : 3.5 20 – 100
RS® X X X 1 : 2 30 – 80
DST X X X X X X 1 : 17 20 – 60
ADS X 1 : 4 10 – 60
SG X 1 : 2 20 – 60
Success Products
Modernization of Combustion Systems 13
All MHPSE burners are of concentric design with swirl flow in all sections and devices such
as fuel nozzle and deflection cones. The CFD supported design ensures best combustion
performance in line with fuel and furnace requirements.
All burners apply staged combustion as an intermediate substoichiometric primary flame
securing low NOX values, combined with sufficient secondary / tertiary air supply even for
overstoichiometric combustion.
Following operational highlights characterize MHPSE-patented burners
■■ Excellent flame stability even under high fuel flexibility
■■ Stable flame attachment to the fuel nozzle
■■ Extensive burner control range with good part load performance
■■ Very low NOX emissions due to focus on pyrolysis and ignition processes
■■ Benefits of stoichiometric / overstoichiometric operation
(less fouling / slagging, corrosion protection)
■■ Easy replacement or adaptation to existing burner
■■ Minimum wear with a minimum 5 years / 24,000 hrs. lifetime guaranteed
Secondary Air Swirler – CFD Optimized Design
14
DS® Burner for Bituminous Coal
DS® Burners were introduced early in the 1990s and continuously developed over the years.
Since 1992 more than 1,500 burners of this type have been successfully placed into operation
and applied both in new installations and rehabilitations. This staged burner type can be used
in direct firing systems for nearly all kinds of pulverized solid fuel qualities.
The burner has a concentric design with swirled flow streams in all burner sections. The DS®
Burner is the first of its kind enabling the above controlled ignition and staged combustion
process. It represents the basis model for the development of the other burner types. Due to
its excellent flame stability, the DS® Burner comes up with a control range of 1: 3.8 whereas
normal coal burners are limited to 1: 2. The burner is suitable for individual combustion air
supply as well as windbox arrangements.
Igniter
Pulverized Fuel
Adjustable Swirlers
Core Air Secondary Air
Tertiary Air
Fuel Nozzle
DS® Burner
DS®W Burner Design for a Windbox Arrangement
DS® Burners are also suitable for biomass co-combustion, as shown with
DS® Burner flame (35 MW), co-combustion coal (60 %) + sawdust (40 %)
Success Products
Modernization of Combustion Systems 15
RS® Burner for Lignite
Logical progression of a successful burner generation comes in the form of RS® Burner
development for lignite combustion. In contrast to conventional jet burners, the innovative
RS® Burner concept is focused on stable fuel ignition at the burner tip.
This principle coming from DS® Burner technology has proved its success in many applications
where existing jet burners have been completely refurbished by burners of this type. Close on
150 burners have been installed at a total of 10 boilers.
The new boiler at Boxberg Unit R (670 MW – commissioned by end of 2011) is the first of
its kind which is equipped with RS® Burners in an “allwallfiring concept”. This convincing
concept – from the arrangement point of view as well – will be applied in all new lignite boilers
designed by MHPSE.
Total control over the lignite combustion process
Under the requirement of keeping to the requested NOX emission values, the RS® Burners permit
overstoichiometric operations – in contrast to jet burners. This has the following advantages:
■■ Reduction of multiple overfire air elevations
■■ Reduction of a slagging tendency due to convenient combustion air supply
■■ Protection against furnace wall corrosion, especially in cases of high fuel sulfur content
MHPSE’s main interest within firing rehabilitation lies in replacing jet burners by RS® Burners
with their favorable operational behavior. It has been proved that this leads to a sustainable
solution of all firing problems.
N. B. Where no RS® Burner refurbishment is intended (e. g. due to budget reasons), MHPSE
can, of course, also upgrade existing jet burners with RS® Burner functionality being used as
much as possible. Precondition: MHPSE’s internal preinvestigation demonstrates that this is
an appropriate measure for meeting the guaranteed performance values.
Secondary Air
Fuel Nozzle
RS® Burner
For further technical details also consult the MHPSE flyer “RS® Burner”
In contrast to the squared jet burners the circular-shaped RS® Burners are equipped with the described features
16
DST Burner for all Predried Pulverized Fuels
The DST Burner has recently been developed on the basis of the DS® Burner concept for use
in indirect firing systems. This burner type is the right one for all kinds of pre-dried pulverized
fuels. Pulverized fuel loading can be amount from 0.5 kg up to 15 kg fuel / kg medium.
These burners have a considerable turndown rate of up to 1:17 and are thus ideal in support
ing flexibility issues. DST Burners can be used for atmospheric operation or in pressurized
systems with air and / or oxyfuel atmosphere. Air, inert gas and flue gas with or without oxygen
enrichment can be used as the delivery medium. An extensive testing program has come up
with a convincing performance in a burner test facility as well as during the test period at the
Oxyfuel pilot plant at the Schwarze Pumpe site.
Biomass, e. g. in the form of pellets or woodchips, can be used
in MHPSE’s DST Burners
Igniter
Core AirSecondary Air
Tertiary Air
Pulverized Fuel
Swirlers Fuel Nozzle
DST Burner
Success Products
Modernization of Combustion Systems 17
ADS Burner – Oil / Gas
ADS Burners are MHPSE’s low-NOX answer to the combustion questions surrounding liquid
and gaseous fuels and which are used with industrial boilers and utility steam generators.
They can be designed as single fuel type burners and for multifuel operation. ADS Burners
are available for the front wall, opposed installation or as bottom burners; they are also used
as startup burners in utility units.
SG Burner – BFG
SG Burners are used for low calorific fuel like Blast Furnace Gas (BFG / BOFG), mulitfuel
applications like COG, NG and oil. For best combustion performance, fuel and air flows are
also influenced by swirlers and other devices.
Oil Gun
Secondary Air
Multi-Spot Gas Nozzles
Adjustable Swirler
SwirlerOil Nozzle
ADS Burner
Contours of temperature: Eshkol Power Station ADS Burner for Gas Firing
Secondary Air BFG COG
NG Primary Air
IgniterOil Gun
SG Burner – BFG
18
Priority in Future Plant Optimization is Shifting
In the past, the main issues have been efficiency and availability for producing power under best
economic conditions from a maximum of plant utilization. In future, besides the network stability
requirement there is also the challenge – even from reduced efficiency and on fulfilling the pro-
gressively tougher emission values – of generating and selling power as often as possible on the
power market during the limited high price conditions so as to secure plant commercial feasibility.
Related challenges of future flexible coal unit operations are
■■ Good part load properties combined with a steeper load ramp
■■ Frequent startups
■■ Extension of coal operation down to lowest minimum load (1mill operation)
■■ Reduction / avoidance of valuable oil / gas during start up, low load
■■ Everything done with consideration given to the existing emission limits (mainly NOX)
From the firing point of view, MHPSE has suitable concepts supported by modern low
emission burner technology as described above. Moreover, MHPSE also possesses
concepts for indirect firing. During energetic optimized operation and / or during low power
prices, fuels are ground and stored independently from the boiler operation and on request
are immediately available. The related integration into existing plants – also in connection with
optional utilization of dried biomass – was investigated by MHPSE in several studies and
is ready for implementation. Solutions to reduce oil and gas under startup optimization con
ditions also exist. System warming by hot gas heating of only one MPS® mill allows early coal
fire for that one mill. This, in turn, takes over overall system heating for the full coal operation,
thus considerably reducing expensive startup fuels. Startup technologies without oil / gas are
being developed.
Fuel flexibility solution (Biomass conversion)
In Europe the trend is towards CO2neutral combustion of biomass such as wood chips, wood
pellets, saw powder and plants / fruits as residues (corn, husk of citrus fruits, olive pits etc.) and
torrefied variants. To this end, MHPSE recommends boiler modifications for cocombustion of
biomass in utility size plants to avoid high investment cost in new plant. MHPSE has suitable
burners for solid biofuels as well as references and concepts for handling, storage and fuel
preparation – and this in partly modified bituminous coal and lignite mills.
Precondition for flexibility – Upfront comprehensive investigation
All the systems involved and their elements such as steam, combustion, flue gas cleaning etc.
need to be investigated in detail as to their eligibility for the intended operational mode.
The main criteria such as full load, NOX emissions, boiler performance, plant integration
and adaptation requirements for fuel logistics – including explosion protection for biomass
application – also need to be considered. MHPSE has the required expertise in overall
solutions for all kinds of flexibility upgrades.
Solutions to Increasing Plant Flexibility
Modernization of Combustion Systems 19
An appropriate configuration of existing technologies will not only significantly increase flexibility
of a coalfired power plant (also one that is optionally biomassfueled) but also contribute –
from cost savings – to greater plant competitiveness. The above scheme shows how to
retrofit a conventional fossilfueled power plant into a hybridfueled, high load and operation
ally flexible power plant – one which assures a maximum utilization of renewable sources and
production of additionally combined heat and power.
By upgrading the firing system with an indirect firing capability 1 it is possible to reduce the
minimum firing rate by approx. 15 %, if permitted by the burner control range. In conjunction
with a retrofit utilizing DST Burners 3 the minimum firing rate can be lowered to about 10 %
thanks to the burners’ wide control range. Below 10 % electrical power can be generated by
using a connected gas turbine, as in the case of gas turbine repowering 5. Implementing an
indirect firing system makes it possible to reach the designed ramp rates of newly build or older
boilers; a reduction of thickness of thick walled components 2 clears the way for reaching a
possible ramp rate of up to 10 % / min. Further ramp rate improvements come from gas turbine
repower ing 5. Thus repowering / topping – using gas turbines either in combined mode
or recovery preheating – makes it possible to improve flexibility by combining two different
generation types in a smart way. It also enables the gross power output to be increased, plant
efficiency enhanced and CO2 emissions cut. The latter can also be achieved by using an
indirect firing system 1 combined with DST Burners 3 burning (e. g.) woody biomass 4.
Operation Improvements
■■ Up to 90 % of costly support fuel can be saved by switching very quickly to
minimum stable coal / biomass load during start up.
■■ Mill operation for the indirect firing system – preferable during offpeak times –
enhances efficiency due to constant mill speed in the optimum energetic range.
■■ Reducing auxiliary power consumption by introducing frequency speed control
to induced and forced draught fans additionally elevates part load efficiency.
G
DST Burner
100% Biomass Capable
Cyclone
Coal Dust Bunker
Conveying
Fan
Air
Raw CoalBunker
�
�
�
�
�
0
10
20
30
40Minimum Load
%�
�
�
Ramp Rate
4
6
8
10
12 %�
�
�
0
+10
+20
+30Power OutputΔ%
�
0
+1
+2
+3Plant Efficiency
Δ%�
–30
–20
–10
0
CO2 Emissions
Δ%
�
�
1 Indirect firing
2 Reduced wall thickness and increase in number of separators / headers
3 DST Burner
4 100 % biomass capable
5 GT repowering
20
Mill Upgrading – Extract
Power Plant Country / MW / Fuel
Mill TypeStart-Up / Retrofit
Retrofit Measure Aim of Retrofit
Frimmersdorf Q Germany / 300 MW / Lig
N 200 1970 / 1998 Retrofit of classifierIncrease of grinding fineness Reduction of temperature
Nanticoke Canada / 512 MW / Bit
E * 1978 / 1998 Retrofit of classifierIncrease of grinding fineness Reduction of unburnt low NOX firing
Reuter Germany / 320 MW / Bit
MPS 170 1987 / 1998Replacement of classifier, sealing system, modification of pf ducts
Increase of grinding fineness Reduction of unburnt low NOX firing
Elverlingsen Germany / 330 MW / Bit
MPS 170 1982 / 1998Replacement of classifier Retrofit of mill
Increase of grinding fineness Reduction of unburnt
Veltheim Germany / 330 MW / Bit
MPS 150 1970 / 1999Replacement of classifier Retrofit of mill
Coal change, capacity increase Increase of grinding fineness Reduction of unburnt
Oroszlany Hungary / 60 MW / Lig
NV 32 1962 / 2000 New design of classifierMill capacity increase Increase of grinding fineness Lifetime extension of wear parts
Neurath C Germany / 300 MW / Lig
DGS 90 1973 / 2000 New rotor, RPM increase Mill capacity increase
Wilhelmshaven Germany / 720 MW / Bit
MPS 235 1976 / 2002Adjust. grinding force, modification of classifier outlet
Mill capacity increase
Niederaußem B Germany / 150 MW / Lig
N * 1962 / 2002 Retrofit of classifier Mill capacity increase
Amer 9 Netherlands / 600 MW / Bit
MPS 235 1992 / 2003 Retrofit of mill parts Conversion to biomass fuel
Heyden Germany / 900 MW / Bit
MPS 255 1987 / 2005Adjust. grinding force, RPM increase, modification of pf ducts
Mill capacity increase
Kiel Germany / 320 MW / Bit
MPS 180 1970 / 2005 Retrofit of dynamic classifier Mill capacity increase
Mehrum Germany / 650 MW / Bit
MPS 1901979 / 2008 / 11
Replacement of classifier (static to dynamic)
Mill capacity incrase Increase of grinding fineness
Weisweiler G,H Germany / 600 MW / Lig
DGS 1301974 / 75 / 2008
Retrofit of mill parts Mill capacity increase
Weisweiler D Germany / 300 MW / Lig
N 80.75 * 1965 / 2008 Retrofit of mill parts Mill capacity increase
Nikola Tesla A Serbia / 308.5 MW / Lig
DGS 1001976 / 2010 / 11 / 12
Redesign of mill parts new rotor, RPM increase
Mill capacity increase Increase of grinding fineness “Low NOX ready”
Kostolac B Serbia / 348.5 MW / Lig
N 275.45 *1991 / 2010 / 12
New design of classifier Retrofit of mill
Mill capacity increase Increase of grinding fineness
Atikokan Canada / 226 MW / Bit
MPS 190 (75 inch)
1985 / 2012 Redesign – engineering of mill parts Conversion to biomass fuel
Altbach Germany / 347.5 MW / Bit
MPS 150 1997 / 2012 RPM increase, new nozzle ringMill capacity increase Reduction of pressure loss
* mills from other suppliers
Rehabilitations – References
Modernization of Combustion Systems 21
Firing Rehabilitations with MHPSE Burners – Extract
Power Plant Country / MW
Burner Type
Fuel Kind of firingNo. of Burners
Burner Load MWth
Year of Commissioning
Sostanj III Slovenia / 275 MW
RS® Lignite Tangential 4 31 1994
Niederaußem B Germany / 150 MW
RS® Lignite Tangential 6 76 1996
Niederaußem A Germany / 150 MW
RS® Lignite Tangential 6 76 1998
EDF Vitry 3 France / 250 MW
DS® Bituminous Front 24 35 1998
EDF Vitry 4 France / 250 MW
DS® Bituminous Front 24 35 1999
Ontario Power, Nanticoke Unit 2 + 4 Canada / 500 MW
DS® Bituminous Opposite 80 35 1999
Cascades Arnsberg, Unit 1 Germany / 60 t / h
DS® Semianthracite Opposite 8 6 1999
Heyden P.S. Germany / 900 MW
DS® Bituminous Opposite 32 66 1999
Ljubljana Boiler 3 Slovenia / 50 MWCHP
RS® Lignite Tangential 12 23 2000
Neurath A Germany / 320 MW
RS® Lignite Tangential 18 58 2000
Neurath B Germany / 320 MW
RS® Lignite Tangential 18 58 2000
Cascades Arnsberg, Unit 2 Germany / 60 t / h
DS® Semianthracite Opposite 8 6 2000
Ontario Power, Nanticoke Unit 1 Canada / 500 MW
DS® Bituminous Opposite 40 35 2000
GKW Kiel Germany / 350 MW
DS® Bituminous Front 24 33 2000
Niederaußem, Unit C1 / C2 Germany / 300 MW
RS® Lignite Roof 2 x 6 76 2001
GKW Hannover, Boiler 1+ 2 Germany / 145 MW
DS® Bituminous Opposite 16 44 2001
Stockstadt, Boiler 9 Germany / 165 t / h
DS® Bituminous Front 4 35 2001
Wilhelmshaven Germany / 800 MW
DS® Bituminous Opposite 32 59 2002
Weiher P.S. Germany / 650 MW
DS® Bituminous Front 24 70 2002
Eshkol C, Boiler 6 + 7 Israel / 230 MW
ADSHeavy fuel oil, natural gas
Opposite 2 x 16 40 2002
Sostanj IV, Unit 5 Slovenia / 345 MW
RS® Lignite Tangential 24 46 2003
Eshkol D, Boiler 8 + 9 Israel / 230 MW
ADSHeavy fuel oil, natural gas
Opposite 2 x 16 40 2003
Ontario Power, Nanticoke Unit 5 Canada / 500 MW
DS® Subbituminous Opposite 40 35 2006
Narcea Spain / 350 MW
DS® Anthracite Roof 24 36 2006
La Robla Spain / 350 MW
DS® Semianthracite Roof 24 36 2007
TENT A5 Serbia / 308.5 MW
RS® Lignite Tangential 18 54 2012
La Cygne – Kansas USA / 715 MW
DS® Subbituminous Opposite 56 35 2012
22
Modernization of Combustion Systems 23
MITSUBISHI HITACHI POWER SYSTEMS
EUROPE GMBH
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