Basic and detailed discussion on Coal Mill (Raymond) and Air Fans Performance in a Thermal Power Plant.
Gives an idea as to how the performance of Coal Mills and fans can be improved
Effect of Coal Quality and Performance of Coal pulverisers / MillsManohar Tatwawadi
The presentation discusses about the change in performance parameters of a pulveriser due to change in coal quality and the measurement of performance and troubleshooting of coal firing system as a whole.
The Presentation discusses the Air-Heater Performance Indices and the Boiler Performance calculation. One can Calculate the air ingress in the air-heater and the boiler and losses incurred thereby. The presentation also describes in details about the boiler efficiency and its calculation.
Basic and detailed discussion on Coal Mill (Raymond) and Air Fans Performance in a Thermal Power Plant.
Gives an idea as to how the performance of Coal Mills and fans can be improved
Effect of Coal Quality and Performance of Coal pulverisers / MillsManohar Tatwawadi
The presentation discusses about the change in performance parameters of a pulveriser due to change in coal quality and the measurement of performance and troubleshooting of coal firing system as a whole.
The Presentation discusses the Air-Heater Performance Indices and the Boiler Performance calculation. One can Calculate the air ingress in the air-heater and the boiler and losses incurred thereby. The presentation also describes in details about the boiler efficiency and its calculation.
This PPT explains the logic and requirement behind Boiler Loss of Flame Protection under MFT. To know more about Boiler Loss of Flame please connect to tahoorkhn03@gmail.com
The main objective of this presentation is that how to optimize the mill in pet coke grinding and what modification is required when changing from normal coal to pet coke.
Turbine Stress Control Logic, Calculation & WorkingTahoor Alam Khan
Turbine Stress Control is one of the complex logics of BHEL turbine. This presentation clearly explains the Logic, working, calculations and influence of the same on operation of steam turbine. For further details and understanding, I can be reached on tahoorkhn03@gmail.com.
Bowl Mill is driven by AC motor, coupled with flexible coupling to the worm shaft. The worm shaft drives worm gear, mounted on the Main Vertical Shaft. A bowl mounted on the top of the shaft rotates at a speed of 40 to 65 rpm. Hot primary air for drying and carrying pulverized coal, enters through insulated Mill side and Liner Assembly.
This PPT explains the logic and requirement behind Boiler Loss of Flame Protection under MFT. To know more about Boiler Loss of Flame please connect to tahoorkhn03@gmail.com
The main objective of this presentation is that how to optimize the mill in pet coke grinding and what modification is required when changing from normal coal to pet coke.
Turbine Stress Control Logic, Calculation & WorkingTahoor Alam Khan
Turbine Stress Control is one of the complex logics of BHEL turbine. This presentation clearly explains the Logic, working, calculations and influence of the same on operation of steam turbine. For further details and understanding, I can be reached on tahoorkhn03@gmail.com.
Bowl Mill is driven by AC motor, coupled with flexible coupling to the worm shaft. The worm shaft drives worm gear, mounted on the Main Vertical Shaft. A bowl mounted on the top of the shaft rotates at a speed of 40 to 65 rpm. Hot primary air for drying and carrying pulverized coal, enters through insulated Mill side and Liner Assembly.
If the material of liner changed with 2RE 69 or Duplex material instead of SS316(urea grade), then passivation air can be reduced, resulting the energy saving because the inerts vented from M.P section and loss of ammonia and problem of pollution. To enhance capacity and energy of the existing plant the internals like vortex mixture and HET may be changed the capacity may increase up to 10-15%.HET, you can changed with super cup.The CO2 and feed top of the vortex mixture nozzle and Ammonia plus carbamate feed from side of the vortex mixture. In the mixing area the initial dispersion of gas and formation of liquid – gas mixture are performed.
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The presentation is based on the discussions of starting operations of a coal based thermal power plant. This presentation is based on the in-house training to the operation engineers of the thermal power plant. It describes the activity chart for the starting of boiler, Turbine and synchronising of Generator, picking up the load etc.
This is a presentation series part 3 on Frequently Asked Questions on Steam Turbines in large steam power plants. All questions are answered properly and any doubt may be mailed to the writer.
Green building concepts and good building practicesManohar Tatwawadi
The power sector must adopt the green building concepts and go for good building practices. In fact all industries need to go for the same. The same practices can also be adopted in all commercial as well as residential buildings.
Auxiliary Consumption and Saving due to Increase in Boiler EfficiencyManohar Tatwawadi
Discussions on Auxiliary consumption in a 4 X 210 MW TPS, the common systems and individual unitwise Auxiliary consumption has been briefed in the presentation. Also savings in various aspects due to increase in Boiler Efficiency are also discussed in the presentation.
COMPRESSED AIR SYSTEM . ENERGY CONSERVATION OPPORTUNITIESManohar Tatwawadi
The presentation gives an idea as to how the compressed air system is designed and the performance of the compressed air system. The losses, conservation of energy, the cost of leakages etc are discussed in the presentation
Questions and answers on turbines used in Power Plants. The discussion is definitely going to reduce your doubts and give you all answers on your questions. This is part 1 and the series will be continued till your doubts are cleared. you can mail me the questions and i will try to give you all answers as early as possible.
The presentation gives a basic idea of cooling towers in big industries including the Power Plants. The performance of cooling towers and the commonenly used terms with reference to the cooling towers are also discussed at length. Care to be taken while in freezing temperatures in the European countries is also discussed.
The presentation is based on the discussions about the safety in Power Plants and substations. The presentation is a part of the seminar on Electrical safety and reliability. The reporting of accidents was also discussed at length in the seminar
Cost accounting, cost control and cost reduction in TPSManohar Tatwawadi
The subject matter discuss in details about the cost accounting being practiced in a thermal power station for calculating the actual cost of generation of electricity. The cost centres and the cost affecting factors alongwith steps to reduce the cost of generation are described in the presentation. The PPMS system adopted can be further be well designed by any power plant engineer.
Environmental and pollution control in Thermal Power StationsManohar Tatwawadi
The presentation gives the basic idea as to the environment, pollutions and laws, the governing bodies and the limits of the emmissions. Also specifically about the solid waste, liquid waste and the gas emmissions from the Thermal Power Plants.
Energy Audit & Energy Conservation Opportunities in Electrical Equipments ...Manohar Tatwawadi
The discussion is for the Energy Conservation drive in the thermal power plants in the Auxilliary Consumption of the Electrical Auxilliaries in the Plant and thereby identify the steps to be taken for the reduction in Auxilliary Consumption
The presentation details the process of combustion in a 500 MW Coal based Thermal Power Plant where the main fuel is Pulverised coal. It details about the combustion of coal partical in the furnace and also the combustion equations related to the process, the excess air that is supplied.
The presentation gives an idea about the primary requirements for the establishment of a coal based THERMAL POWER STATION. The estimates are quite fair.
The presentation details about the Boiler Operation specifically while lightup of boiler and loading of boiler. the course participants discuss in details about the operations carried in their respective power stations
The discussion on "Handling of Turbines During Emergencies" has been detailed in the ppt. Some case studies are also discussed in the session where the course participants express their difficulties while coming across the emergencies in handling the turbines at their locations.
The Presentation describes the basics about the Efficiency and performance of a steam based power plant. It also describes how the heat rate of the power plant is important from the point of view of fuel savings.
THE PRESENTATION SPEAKS ABOUT THE BASIC IDEAS ABOUT EFFICIENCIES OF BOILER AND TURBINE IN A COAL BASED THERMAL POWER PLANT WITH THE DESIGN EFFICIENCIES AND HEAT RATE. IT ALSO THROWS LIGHT ON THE VARIOUS IMPROVEMENTS IN HEAT RATE AND EFFICIENCIES.THAT CAN BE ACHIEVED.
Alt. GDG Cloud Southlake #33: Boule & Rebala: Effective AppSec in SDLC using ...James Anderson
Effective Application Security in Software Delivery lifecycle using Deployment Firewall and DBOM
The modern software delivery process (or the CI/CD process) includes many tools, distributed teams, open-source code, and cloud platforms. Constant focus on speed to release software to market, along with the traditional slow and manual security checks has caused gaps in continuous security as an important piece in the software supply chain. Today organizations feel more susceptible to external and internal cyber threats due to the vast attack surface in their applications supply chain and the lack of end-to-end governance and risk management.
The software team must secure its software delivery process to avoid vulnerability and security breaches. This needs to be achieved with existing tool chains and without extensive rework of the delivery processes. This talk will present strategies and techniques for providing visibility into the true risk of the existing vulnerabilities, preventing the introduction of security issues in the software, resolving vulnerabilities in production environments quickly, and capturing the deployment bill of materials (DBOM).
Speakers:
Bob Boule
Robert Boule is a technology enthusiast with PASSION for technology and making things work along with a knack for helping others understand how things work. He comes with around 20 years of solution engineering experience in application security, software continuous delivery, and SaaS platforms. He is known for his dynamic presentations in CI/CD and application security integrated in software delivery lifecycle.
Gopinath Rebala
Gopinath Rebala is the CTO of OpsMx, where he has overall responsibility for the machine learning and data processing architectures for Secure Software Delivery. Gopi also has a strong connection with our customers, leading design and architecture for strategic implementations. Gopi is a frequent speaker and well-known leader in continuous delivery and integrating security into software delivery.
Enhancing Performance with Globus and the Science DMZGlobus
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Why You Should Replace Windows 11 with Nitrux Linux 3.5.0 for enhanced perfor...SOFTTECHHUB
The choice of an operating system plays a pivotal role in shaping our computing experience. For decades, Microsoft's Windows has dominated the market, offering a familiar and widely adopted platform for personal and professional use. However, as technological advancements continue to push the boundaries of innovation, alternative operating systems have emerged, challenging the status quo and offering users a fresh perspective on computing.
One such alternative that has garnered significant attention and acclaim is Nitrux Linux 3.5.0, a sleek, powerful, and user-friendly Linux distribution that promises to redefine the way we interact with our devices. With its focus on performance, security, and customization, Nitrux Linux presents a compelling case for those seeking to break free from the constraints of proprietary software and embrace the freedom and flexibility of open-source computing.
Accelerate your Kubernetes clusters with Varnish CachingThijs Feryn
A presentation about the usage and availability of Varnish on Kubernetes. This talk explores the capabilities of Varnish caching and shows how to use the Varnish Helm chart to deploy it to Kubernetes.
This presentation was delivered at K8SUG Singapore. See https://feryn.eu/presentations/accelerate-your-kubernetes-clusters-with-varnish-caching-k8sug-singapore-28-2024 for more details.
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Today, after several years of existence, an extremely active community and an ultra-dynamic ecosystem, Kubernetes has established itself as the de facto standard in container orchestration. Thanks to a wide range of managed services, it has never been so easy to set up a ready-to-use Kubernetes cluster.
However, this ease of use means that the subject of security in Kubernetes is often left for later, or even neglected. This exposes companies to significant risks.
In this talk, I'll show you step-by-step how to secure your Kubernetes cluster for greater peace of mind and reliability.
Smart TV Buyer Insights Survey 2024 by 91mobiles.pdf91mobiles
91mobiles recently conducted a Smart TV Buyer Insights Survey in which we asked over 3,000 respondents about the TV they own, aspects they look at on a new TV, and their TV buying preferences.
zkStudyClub - Reef: Fast Succinct Non-Interactive Zero-Knowledge Regex ProofsAlex Pruden
This paper presents Reef, a system for generating publicly verifiable succinct non-interactive zero-knowledge proofs that a committed document matches or does not match a regular expression. We describe applications such as proving the strength of passwords, the provenance of email despite redactions, the validity of oblivious DNS queries, and the existence of mutations in DNA. Reef supports the Perl Compatible Regular Expression syntax, including wildcards, alternation, ranges, capture groups, Kleene star, negations, and lookarounds. Reef introduces a new type of automata, Skipping Alternating Finite Automata (SAFA), that skips irrelevant parts of a document when producing proofs without undermining soundness, and instantiates SAFA with a lookup argument. Our experimental evaluation confirms that Reef can generate proofs for documents with 32M characters; the proofs are small and cheap to verify (under a second).
Paper: https://eprint.iacr.org/2023/1886
The Art of the Pitch: WordPress Relationships and SalesLaura Byrne
Clients don’t know what they don’t know. What web solutions are right for them? How does WordPress come into the picture? How do you make sure you understand scope and timeline? What do you do if sometime changes?
All these questions and more will be explored as we talk about matching clients’ needs with what your agency offers without pulling teeth or pulling your hair out. Practical tips, and strategies for successful relationship building that leads to closing the deal.
Pushing the limits of ePRTC: 100ns holdover for 100 daysAdtran
At WSTS 2024, Alon Stern explored the topic of parametric holdover and explained how recent research findings can be implemented in real-world PNT networks to achieve 100 nanoseconds of accuracy for up to 100 days.
PHP Frameworks: I want to break free (IPC Berlin 2024)Ralf Eggert
In this presentation, we examine the challenges and limitations of relying too heavily on PHP frameworks in web development. We discuss the history of PHP and its frameworks to understand how this dependence has evolved. The focus will be on providing concrete tips and strategies to reduce reliance on these frameworks, based on real-world examples and practical considerations. The goal is to equip developers with the skills and knowledge to create more flexible and future-proof web applications. We'll explore the importance of maintaining autonomy in a rapidly changing tech landscape and how to make informed decisions in PHP development.
This talk is aimed at encouraging a more independent approach to using PHP frameworks, moving towards a more flexible and future-proof approach to PHP development.
Essentials of Automations: The Art of Triggers and Actions in FMESafe Software
In this second installment of our Essentials of Automations webinar series, we’ll explore the landscape of triggers and actions, guiding you through the nuances of authoring and adapting workspaces for seamless automations. Gain an understanding of the full spectrum of triggers and actions available in FME, empowering you to enhance your workspaces for efficient automation.
We’ll kick things off by showcasing the most commonly used event-based triggers, introducing you to various automation workflows like manual triggers, schedules, directory watchers, and more. Plus, see how these elements play out in real scenarios.
Whether you’re tweaking your current setup or building from the ground up, this session will arm you with the tools and insights needed to transform your FME usage into a powerhouse of productivity. Join us to discover effective strategies that simplify complex processes, enhancing your productivity and transforming your data management practices with FME. Let’s turn complexity into clarity and make your workspaces work wonders!
Transcript: Selling digital books in 2024: Insights from industry leaders - T...BookNet Canada
The publishing industry has been selling digital audiobooks and ebooks for over a decade and has found its groove. What’s changed? What has stayed the same? Where do we go from here? Join a group of leading sales peers from across the industry for a conversation about the lessons learned since the popularization of digital books, best practices, digital book supply chain management, and more.
Link to video recording: https://bnctechforum.ca/sessions/selling-digital-books-in-2024-insights-from-industry-leaders/
Presented by BookNet Canada on May 28, 2024, with support from the Department of Canadian Heritage.
Removing Uninteresting Bytes in Software FuzzingAftab Hussain
Imagine a world where software fuzzing, the process of mutating bytes in test seeds to uncover hidden and erroneous program behaviors, becomes faster and more effective. A lot depends on the initial seeds, which can significantly dictate the trajectory of a fuzzing campaign, particularly in terms of how long it takes to uncover interesting behaviour in your code. We introduce DIAR, a technique designed to speedup fuzzing campaigns by pinpointing and eliminating those uninteresting bytes in the seeds. Picture this: instead of wasting valuable resources on meaningless mutations in large, bloated seeds, DIAR removes the unnecessary bytes, streamlining the entire process.
In this work, we equipped AFL, a popular fuzzer, with DIAR and examined two critical Linux libraries -- Libxml's xmllint, a tool for parsing xml documents, and Binutil's readelf, an essential debugging and security analysis command-line tool used to display detailed information about ELF (Executable and Linkable Format). Our preliminary results show that AFL+DIAR does not only discover new paths more quickly but also achieves higher coverage overall. This work thus showcases how starting with lean and optimized seeds can lead to faster, more comprehensive fuzzing campaigns -- and DIAR helps you find such seeds.
- These are slides of the talk given at IEEE International Conference on Software Testing Verification and Validation Workshop, ICSTW 2022.
2. Load Swings
• Today’s demands on PC-fired unit flexibility are
tremendous. Even very large units are now
expected to park overnight at low loads before
rapidly ramping up in the morning for another
day of load swings.
• This combined with new requirements for NOx
reduction and a market-driven push for fuel
flexibility has taxed coal pulverizing equipment to
the limit.
• The utility staff can, however, hold its own against
such odds if it takes the time to understand the
pulverizers and properly set them up.
5/10/2019 2Manohar Tatwawadi
3. Pulveriser Designs
One of the most popular pulverizer designs in
use today is the medium speed roll and race
design, such as B&W’s MPS, Foster Wheeler’s
MB or MBF, and ABB-CE’s new HP. This type of
design will be generically addressed here. All
curves and examples presented are consistent
with a theoretical, but practical example of an
operating roll and race design.
5/10/2019 3Manohar Tatwawadi
5. Pulveriser Setup & Tuning
• Pulverizer set up and tuning will be addressed
in three parts:
• Part I - Pulverizer Capacity
• Part II - Primary Air/Fuel Ratio
Characterization
• Part III - Pulverizer Controls
5/10/2019 5Manohar Tatwawadi
6. Pulveriser Capacity
• When a pulverizer manufacturer rates
capacity at 100,000 pph, (45 TPH) there are
strings attached. Associated with that rating
are limits on coal grindability, moisture, feed
size and output fineness, along with some
reasonable PA/fuel ratio.
• Each of the parameters will affect the effective
size of the machine.
5/10/2019 6Manohar Tatwawadi
7. Grindability Index and Capacity
Mill Capacity – 125ooo Lb/hr
Case -1
HGI Index – 55%
Capacity to grind 70% thro 200
mesh – 133000 Lb/hr
Case – 2
HGI Index – 50%
Capacity to grind 70% thro 200
mesh – 122000 Lb/hr
Case – 3
HGI Index – 40%
Capacity to grind 80% thro 200
mesh – 85000 Lb/hr.
5/10/2019 Manohar Tatwawadi 7
12. Capacity…
• For example, consider a 100 KPPH (45360 kg/hr)
pulverizer which was designed for a Hardgrove
Grindability Index (HGI) of 60, a surface moisture of
less than 10%, and a feed size of 2.5".
• The 100 KPPH (45.36 T/hr) rating means that
operating at those stated conditions the pulverizer
product will have a fineness of 70% through a 200
mesh at a throughput of 45.36 TPH.
• Figures No. 1 through 4 shows how the capacity of
the pulverizer actually changes as each of the
operating parameters change.
• Figures No. 1, 3 and 4 assume that rated fineness is
being maintained, which in this case is 70% through
200 mesh.
5/10/2019 12Manohar Tatwawadi
13. Pulveriser Capacity
• Suppose a plant’s fuels department has found a
bargain on a local coal which has an HGI of 54, a
surface moisture of 14% and a feed size of 2.75".
Using the capacity correction curves, the
pulverizers new effective capacity for delivering a
70% through 200 mesh product is:
• (RATED CAPACITY) (HGI CORRECTION) (MOISTURE
CORRECTION) (SIZE CORRECTION) = (100 KPPH)
(.935) (.97) = 82.5 KPPH
5/10/2019 13Manohar Tatwawadi
14. Capacity Curves & Relations
• If the operators simply must push 100 KPPH of
this new fuel through the pulverizer, then
Figure No. 2 indicates that the pulverizer will
be running at 121% of the new rated capacity
and the 200 mesh fineness will drop to about
52%. There goes LOI and boiler efficiency, not
to mention an increase in equipment erosion
and possible adverse effects on NOX.
5/10/2019 14Manohar Tatwawadi
15. Inside the mill
The profile of
the roll should
be parallel with
the grinding ring
profile.
5/10/2019 Manohar Tatwawadi 15
17. Classifiers
• The flow of coal particles through a classifier is
several times the amount of coal flowing to the
burners because of the large amount of coal
recirculated within a pulverizer. For example, if a
pulverizer is operating at 100,000 lb/hr coal feed to
the burners, as much as 300,000 lb/hr or more may
be flowing through the classifier for regrinding. For
this reason the surface smoothness and inverted
cone clearances or discharge doors of the MPS
original design mills are extremely important for
acceptable pulverizer performance and of course,
optimum furnace performance.
5/10/2019 Manohar Tatwawadi 17
18. Effects / Results
• Pulverizer performance will deteriorate any time the
machine is operated above its effective rating. The
above example of switching fuels is one illustration, but
a similar effect may result from switching to a fuel with
lower heating value or trying to sustain higher loads with
fewer pulverizers operating. Both increase the required
fuel throughput. It is a certainty that LOI goes up as
fineness goes down.
• The message then, is to thoroughly consider the rating
and operating conditions of the pulverizer before firming
up new fuel purchases or buying new pulverizers. Other
fuels impacts such as fouling and slagging tendencies,
fuel bound nitrogen, sulfur and ash should be considered
as well.5/10/2019 18Manohar Tatwawadi
19. PRIMARY AIR/FUEL RATIO
CHARACTERIZATION
The primary air/fuel ratio characterization is a
very critical but seldom understood curve. Even
the manufacturer’s start-up or service engineer
sometimes fails to grasp the significance of the
relationship as a whole, or the effect of each part
of the curve. How the air/fuel ratio is
characterized will have profound effects on flame
stability, pulverizer load stability, turndown,
response rate, burner eyebrows, NOx generation,
LOI, erosion and auxiliary power use.
5/10/2019 19Manohar Tatwawadi
20. MINIMUM ALLOWABLE CURVE
The exact values of PA Flow for a given pulverizer are a function of coal
conduit size, fuel moisture and throat ring flow area. In any case the
actual curve must be above a minimum allowable curve.
5/10/2019 20Manohar Tatwawadi
21. Components of Minimum Air Flow
• The minimum curve has four components which must be
calculated and coordinated: Minimum line velocity,
minimum A/F ratio, minimum slope, and the resulting
inflection point.
• The minimum line velocity is the velocity required through
the coal conduits to keep the fuel in suspension. At lower
PA flows the pulverized coal is in danger of falling out of
suspension and laying out in the coal conduits, possibly
resulting in fire or explosion. Minimum line velocity is thus
affected by conduit size, number of conduits, altitude and
temperature. Minimum line velocity is usually targeted at
about 3000 fpm (15.24 m/sec) at sea level. The quantity of
air required to maintain minimum line velocity is calculated
as follows:
5/10/2019 21Manohar Tatwawadi
22. The minimum line velocity
Carrying of Particles by Fluid Drag
In view of the age of the technique it would be presumed that the
subject of concurrent fluid-solid flow would be quite well defined
and understood.
Investigation of the published literature indicates, however, that
such conveying is still an extremely empirical art.
5/10/2019 Manohar Tatwawadi 22
23. Pneumatic Carrying of Particles
• The major goal of pneumatic conveying of solids is to maximize the
carrying capacity of the installation and carry flows with high-solids
concentration ("dense-phase flow").
• In pulverized coal combustion, the ratio of coal to carrying gas is
usually in the range of y = 0.5-0.6 kg/kg.
• Assuming a coal density rc = 1.5 x 103 kg/m3, and the density of the
carrying gas as rg = 0.9 kg/m 3, the volume fraction of the coal can be
shown to be very small, 0.036 % .
• Dilute Phase Transport
• The inter particle effects can therefore be neglected for steady state
operation.
• An important aerodynamic characteristic of the particles is their
terminal velocity (the free-fall velocity in stagnant air) which for a
spherical particle of d = 0.1 mm has an approximate value of
0.3m/sec.
• Experience shows that due to non-uniformities of flow behind bends,
and to avoid settling of solids in horizontal sections of the transport
line, a gas velocity of ~ V = 16 -- 20 m/sec has to be chosen.
5/10/2019 Manohar Tatwawadi 23
24. Qty of Air for Minimum Velocity
• Minimum line velocity is usually targeted at about 3000
fpm (15.24 m/sec) at sea level. The quantity of air required
to maintain minimum line velocity is calculated as follows:
• Air Flow = (3000fpm) (60 min/hr) (A) (N) (p) Po/Pb
Where:
• A = Flow Area of one conduit, ft2
• N = No. Of conduits/pulverizer
• Po= Standard barometric pressure, psiu
• Pb= Barometric pressure at plant altitude, psiu
• p = Density of air at standard pressure, 150°F. (65.50C)
• Note: Western fuels are often controlled to 135°F, which
would also require a density correction for temperature.
5/10/2019 24Manohar Tatwawadi
25. Min PA Flow Required
• Thus, for user example pulverizer, the PA flow required to
support minimum line velocity is calculated at 150°F,
elevation of 400 ft., and four 17" I.D. coal conduits per
pulverizer:
(3000fpm) (60 min/hr) π (17 in)2 (4) (0.00651 lb/ft3) (14.7 psia)
(4) (144 in2/ft2) (14.44 psia)
• = 75,212 pph
5/10/2019 25Manohar Tatwawadi
26. Min. Allowable PA/Fuel Ratio
• Function of Moisture in Fuel
• Note also that minimum air/fuel ratio is achieved at maximum fuel flow.
• Thus, multiplying the maximum fuel flow by the minimum air/fuel ratio
results in the PA flow at maximum fuel flow. Continuing our example:
• Max PA Flow = (100,000 pph fuel flow) (1.25 lb air/lb fuel) = 125,000 pph
5/10/2019 26Manohar Tatwawadi
27. Operating Range of PA Flow
Typical turndown ratio for this type of pulverizer is between 2-1/2 and 3 to 1,
which would put minimum operating load at 33.3 to 40 kpph in the example.
Thus, an inflection point of 33.3 kpph would seem in order.
5/10/2019 27Manohar Tatwawadi
28. Lower PA FLOW
· Improved fineness
· Less component erosion
· More complete pyrite rejection
· Fewer or smaller burner eyebrows (via better pyrite rejection)
· Less PA fan capacity requirements
· Less PA system resistance (not including the pulverizer)
· More reserve fines available
· Greater opportunity for steeper characterization curve
· Easier to keep inflection point out of the operating range
· Aids in NOX reduction
· Higher pulveriser d/p via increased bed depth
· Excessive pyrites & fuel rejection via low throat ring velocity
· Increased fire risk due to operating closer to minimum line velocity & minimum
throat ring velocity
· Greater tendency to plug with wet coal
· Hotter inlet air temperature (i.e. constant BTU input) for the same fuel moisture5/10/2019 28Manohar Tatwawadi
29. Operational Makeovers
• The higher d/p may be handled through additional PA fan head, if
available.
• The increased fire risk is really not a factor if operated as described above.
• Wet coal pluggage with reduced PA flow can be avoided bias available
until maximum biased air flow prior to the change (assuming this previous
maximum air flow adequately avoided wet pluggage).
• Excessive pyrites rejection is a matter of insufficient throat ring velocity,
however, and may require mechanical modification of the throat ring flow
area. Minimum throat ring velocity varies with pulverizer design, and
even seems to be somewhat proprietary among manufacturers.
• Obviously, the proper minimum velocity is that which provides continued
fuel through put while rejecting the majority of legitimate pyrites but very
little fuel. Once again, field test at low pulverizer load will determine what
needs to be done.
• If PA flow has been lowered then one good approach would be to add
throat ring flow area restriction proportionally to maintain the same
velocity.
5/10/2019 29Manohar Tatwawadi
30. Primary Air Lead & Lags
• A load-following unit with rapid load changes
requires maximum pulverizer ramping capability.
• During a pulverizer load ramp the primary air will
always lead the increase ramps (transferring
additional fines to the burners) and lag the
decrease ramps (to withhold fines from the
burners). Once the new load is reached both fuel
and air find a new equilibrium point as
determined by the characterization curve.
• The faster the ramp, the more the primary air
leads (or lags) the fuel.
5/10/2019 30Manohar Tatwawadi
31. Derate Analysis and Operating Concerns
• Pulverizer capacity limitation : A derate is due to the fuel
burn rate exceeding predicted pulverizer capacity with all
pulverizers in service.
• Feeder capacity limitation : A derate is due to the fuel
burn rate is greater than the total actual feeder capacity
with all pulverizers in service.
• An exhauster mill limitation: A derate is due to the
calculated airflow required with all pulverizers in service is
greater than the actual exhauster fan flow.
• Improper pulverizer outlet temperature: A derate is due to
the heat available in the primary air for drying coal in the
pulverizers is less than that required.
5/10/2019 Manohar Tatwawadi 31
32. Mill Units Design A B C D E F G H
Plant load MW 500 491.67 494.33 464.67 464.17 504.33 519.33 496.80 487.70
Coal flow t/h 51.248 59.56 56.42 54.28 56.42 57.51 56.68 58.40 56.47
A/F ratio 2.03 2.09 2.12 2.08 2.15 2.13 2.16 2.15 2.12
PA temp. oC 243 247.17 244.67 245.00 246.33 247.50 241.50 245.17 248.50
Coal-air mixture
temp
oC 85 78 76 81 72 71 70 75 75
Coal fineness
below 75 micron
% 70 65 68 70 60 61 62 61 62
DP mmWC 437.9 494.00 496.83 485.50 467.83 440.33 430.50 496.50 431.90
PA pressure I/L mmWC 991.5 900.50 927.50 999.83 909.67 922.33 933.50 929.17 958.80
PA flow t/h 104 120.31 123.01 110.52 102.18 104.80 108.66 113.13 120.17
Power kW 406 393.72 404.22 458.29 379.51 382.57 365.17 445.18 428.11
Energy kWh/h - 383.52 395.76 451.92 370.62 374.22 350.94 441.48 433.12
Load factor % 84.58 82.03 84.21 95.48 79.06 79.70 76.08 92.75 89.19
Sp. Energy
Consumption
kWh/t of
coal
7.92 8.44 9.01 8.33 8.57 8.51 8.19 8.56 8.67
Performance results of mills for 500 MW plant.
5/10/2019 Manohar Tatwawadi 32