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.
Non recovery-heat recovery cokemaking - a review of recent developmentsJorge Madias
This paper is an update of a previous publication in Spanish [1]. One of the current trends in the production of
metallurgical coke is the comeback of non-recovery ovens. This is driven by less interest in byproducts, smaller investment per annual ton, better environmental performance. The development took place particularly in China, India, USA, Brazil, Australia and Colombia [2]. In the USA, one important factor promoting this technology was that EPA declared it as Maximum Achievable Current technology in 1990. This technology arises from the classic beehive ovens which supplied since the XVIII century the coke for the industrial revolution. Those ovens were manually operated, with small heat recovery, just for heating the oven. Now, non-recovery ovens are modern construction, with highly mechanized operation, and automated to a certain degree. Gases generated by the combustion of the volatile matter are sent through downcomers and further burnt to heat the oven bottom and sides; in many cases, mostly when the plant is built within or closed to a steelmaking facility, the hot gas is used for vapor generation and electric power production. Main differences between conventional and non-recovery/heat recovery processes are shown in figure 1. In conventional process, the coal charged receives the heat indirectly through the furnace walls, by combustion of external gas; inside the oven, positive pressure develops. Gas generated in the coking process is sent to the
by-products plant. In non-recovery ovens, coking proceeds from the top through direct heating by the partial
combustion of the volatile matter over the coal bed, and from the bottom by heat coming from full combustion of gases escaping from the oven. In these plants, the offgas is treated and sent to the stack, in many cases after recovering sensible heat to produce vapor and electric power. Installed capacity for these furnaces was esteemed in 2005 in 22 M metric tons per year, probably including
beehive ovens [2]. In table 1, some of the non-recovery coke plants currently operating are listed. Some plants
belong to companies with coal mining as its core business; others are independent coke producers, purchasing coal and selling coke; then there is some joint ventures between coke producers and steelmakers,
and finally, captive coke plants belonging to steel companies.
Combustion is a chemical process in which a substance reacts rapidly with oxygen and gives off heat. The original substance is called the fuel, and the source of oxygen is called the oxidizer. The fuel can be a solid, liquid, or gas, although for airplane propulsion the fuel is usually a liquid. The oxidizer, likewise, could be a solid, liquid, or gas.
Non recovery-heat recovery cokemaking - a review of recent developmentsJorge Madias
This paper is an update of a previous publication in Spanish [1]. One of the current trends in the production of
metallurgical coke is the comeback of non-recovery ovens. This is driven by less interest in byproducts, smaller investment per annual ton, better environmental performance. The development took place particularly in China, India, USA, Brazil, Australia and Colombia [2]. In the USA, one important factor promoting this technology was that EPA declared it as Maximum Achievable Current technology in 1990. This technology arises from the classic beehive ovens which supplied since the XVIII century the coke for the industrial revolution. Those ovens were manually operated, with small heat recovery, just for heating the oven. Now, non-recovery ovens are modern construction, with highly mechanized operation, and automated to a certain degree. Gases generated by the combustion of the volatile matter are sent through downcomers and further burnt to heat the oven bottom and sides; in many cases, mostly when the plant is built within or closed to a steelmaking facility, the hot gas is used for vapor generation and electric power production. Main differences between conventional and non-recovery/heat recovery processes are shown in figure 1. In conventional process, the coal charged receives the heat indirectly through the furnace walls, by combustion of external gas; inside the oven, positive pressure develops. Gas generated in the coking process is sent to the
by-products plant. In non-recovery ovens, coking proceeds from the top through direct heating by the partial
combustion of the volatile matter over the coal bed, and from the bottom by heat coming from full combustion of gases escaping from the oven. In these plants, the offgas is treated and sent to the stack, in many cases after recovering sensible heat to produce vapor and electric power. Installed capacity for these furnaces was esteemed in 2005 in 22 M metric tons per year, probably including
beehive ovens [2]. In table 1, some of the non-recovery coke plants currently operating are listed. Some plants
belong to companies with coal mining as its core business; others are independent coke producers, purchasing coal and selling coke; then there is some joint ventures between coke producers and steelmakers,
and finally, captive coke plants belonging to steel companies.
Combustion is a chemical process in which a substance reacts rapidly with oxygen and gives off heat. The original substance is called the fuel, and the source of oxygen is called the oxidizer. The fuel can be a solid, liquid, or gas, although for airplane propulsion the fuel is usually a liquid. The oxidizer, likewise, could be a solid, liquid, or gas.
The slides describe the factors that affect the performance of AFBC boilers and how to improve the performance of AFBC boilers. These type of boilers are mainly used in the below 100 MW power boilers.
The presentation is about the fuels used in the Thermal Power Plants and the combustion taking place in large pulverised coal boilers. The calculations about the Air requirements for complete combustion of fuels in the boilers.
The slides describe the factors that affect the performance of AFBC boilers and how to improve the performance of AFBC boilers. These type of boilers are mainly used in the below 100 MW power boilers.
The presentation is about the fuels used in the Thermal Power Plants and the combustion taking place in large pulverised coal boilers. The calculations about the Air requirements for complete combustion of fuels in the boilers.
Three basic methods used to control engine emissions:
1)Engineering of combustion process -advances in fuel injectors, oxygen sensors, and on-board computers.
2) Optimizing the choice of operating parameters -two Nox control measures that have been used in automobile engines are spark retard and EGR.
3) After treatment devices in the exhaust system -catalytic converter.
Biomass gasification is a chemical process that convert
biomass into useful convenient gaseous fuel. It has emerged as a promising technology to fulfill the increasing energy demands of the world as well as to reduce significantly the volume of Biomass waste generated in developing societies.
Gasification produce gases like CO,CO2, H2 and CH4; these gas released are called Syngas.
Gasification technology can be used for:
Household Fuel
Electricity and Steam Generation
In internal combustion engines as a fuel
In a gasifier, the biomass undergoes several different processes like drying, pyrolysis, combustion and gasification process
Pollutant,their formation and control in Internal Combustion EnginesHassan Raza
This presentation was prepared by Mechanical Engineering students during their Internal Combustion Course. Students belong to a very prestigious Engineering institute of Pakistan "University of Engineering and Technology Lahore"
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 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.
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 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.
Vaccine management system project report documentation..pdfKamal Acharya
The Division of Vaccine and Immunization is facing increasing difficulty monitoring vaccines and other commodities distribution once they have been distributed from the national stores. With the introduction of new vaccines, more challenges have been anticipated with this additions posing serious threat to the already over strained vaccine supply chain system in Kenya.
COLLEGE BUS MANAGEMENT SYSTEM PROJECT REPORT.pdfKamal Acharya
The College Bus Management system is completely developed by Visual Basic .NET Version. The application is connect with most secured database language MS SQL Server. The application is develop by using best combination of front-end and back-end languages. The application is totally design like flat user interface. This flat user interface is more attractive user interface in 2017. The application is gives more important to the system functionality. The application is to manage the student’s details, driver’s details, bus details, bus route details, bus fees details and more. The application has only one unit for admin. The admin can manage the entire application. The admin can login into the application by using username and password of the admin. The application is develop for big and small colleges. It is more user friendly for non-computer person. Even they can easily learn how to manage the application within hours. The application is more secure by the admin. The system will give an effective output for the VB.Net and SQL Server given as input to the system. The compiled java program given as input to the system, after scanning the program will generate different reports. The application generates the report for users. The admin can view and download the report of the data. The application deliver the excel format reports. Because, excel formatted reports is very easy to understand the income and expense of the college bus. This application is mainly develop for windows operating system users. In 2017, 73% of people enterprises are using windows operating system. So the application will easily install for all the windows operating system users. The application-developed size is very low. The application consumes very low space in disk. Therefore, the user can allocate very minimum local disk space for this application.
Welcome to WIPAC Monthly the magazine brought to you by the LinkedIn Group Water Industry Process Automation & Control.
In this month's edition, along with this month's industry news to celebrate the 13 years since the group was created we have articles including
A case study of the used of Advanced Process Control at the Wastewater Treatment works at Lleida in Spain
A look back on an article on smart wastewater networks in order to see how the industry has measured up in the interim around the adoption of Digital Transformation in the Water Industry.
Cosmetic shop management system project report.pdfKamal Acharya
Buying new cosmetic products is difficult. It can even be scary for those who have sensitive skin and are prone to skin trouble. The information needed to alleviate this problem is on the back of each product, but it's thought to interpret those ingredient lists unless you have a background in chemistry.
Instead of buying and hoping for the best, we can use data science to help us predict which products may be good fits for us. It includes various function programs to do the above mentioned tasks.
Data file handling has been effectively used in the program.
The automated cosmetic shop management system should deal with the automation of general workflow and administration process of the shop. The main processes of the system focus on customer's request where the system is able to search the most appropriate products and deliver it to the customers. It should help the employees to quickly identify the list of cosmetic product that have reached the minimum quantity and also keep a track of expired date for each cosmetic product. It should help the employees to find the rack number in which the product is placed.It is also Faster and more efficient way.
Industrial Training at Shahjalal Fertilizer Company Limited (SFCL)MdTanvirMahtab2
This presentation is about the working procedure of Shahjalal Fertilizer Company Limited (SFCL). A Govt. owned Company of Bangladesh Chemical Industries Corporation under Ministry of Industries.
Immunizing Image Classifiers Against Localized Adversary Attacksgerogepatton
This paper addresses the vulnerability of deep learning models, particularly convolutional neural networks
(CNN)s, to adversarial attacks and presents a proactive training technique designed to counter them. We
introduce a novel volumization algorithm, which transforms 2D images into 3D volumetric representations.
When combined with 3D convolution and deep curriculum learning optimization (CLO), itsignificantly improves
the immunity of models against localized universal attacks by up to 40%. We evaluate our proposed approach
using contemporary CNN architectures and the modified Canadian Institute for Advanced Research (CIFAR-10
and CIFAR-100) and ImageNet Large Scale Visual Recognition Challenge (ILSVRC12) datasets, showcasing
accuracy improvements over previous techniques. The results indicate that the combination of the volumetric
input and curriculum learning holds significant promise for mitigating adversarial attacks without necessitating
adversary training.
Democratizing Fuzzing at Scale by Abhishek Aryaabh.arya
Presented at NUS: Fuzzing and Software Security Summer School 2024
This keynote talks about the democratization of fuzzing at scale, highlighting the collaboration between open source communities, academia, and industry to advance the field of fuzzing. It delves into the history of fuzzing, the development of scalable fuzzing platforms, and the empowerment of community-driven research. The talk will further discuss recent advancements leveraging AI/ML and offer insights into the future evolution of the fuzzing landscape.
2. FUELS
• Generally three types of Fuels are used in
Coal Based Thermal Power Stations
1. Light Diesel Oil
2. Furnace Oil / LSHS and
3. Pulverised Coal
• Liquid Fuels are generally used for initial
starting, or for stabilisation of flame.
16-Dec-2021 Manohar Tatwawadi 2
Liquid Fuels
4. 16-Dec-2021
FUEL PROPERTIES
LIQUID FUEL PROPERTIES
VISCOSITY
• SPECIFIED IN STROKES/ CENTISTROKES REDWOOD,
ENGLER OR SAYBOLT
• DEPENDS ON TEMPERATURE
• DECREASES AS TEMP INCREASES
• INFLUENCES THE DEGREE OF PREHEAT
REQUIRED FOR PUMPING, BURNING,
ATOMISATION (MAY CAUSE CARBON
DEPOSITS ON BURNER TIPS)
4
Manohar Tatwawadi
5. 16-Dec-2021
FUEL PROPERTIES
LIQUID FUEL PROPERTIES
• FLASH POINT 66 0 C
• POUR POINT FOR PUMPABLITY
• SPECIFIC HEAT 0.22-0.28 kCal/K0C (determine how
much steam will be required for pre heating)
FUEL GCV S% FUEL GCV S%
KEROSENE 11100 .05-0.2 DIESEL OIL 10800 0.05-0.25
L.D.O. 10700 0.5-1.8 F.O. 10500 2.0-4.0
L.S.H.S. 10600 < 0.5
(GCV:- Gross Calorific Value in kCal/kg, S%:- Sulphur %)
5
Manohar Tatwawadi
6. 16-Dec-2021
LIQUID FUELS
STORAGE
SIZING:- GENERALLY 10 DAYS CAPACITY
TANKS:- VERTICAL ABOVE GROUND WITH BUND WALLS
CLEANING:- ANNUALY FOR HEAVY AND 2YRS FOR LIGHT
ALL LEAKS FROM JOINTS, FLANGES AND PIPELINES
MUST BE ARRESTED
LOSS OF ONE DROP OF OIL EVERY SECOND CAN
COST OVER 4000 LTRS AN YEAR
6
Manohar Tatwawadi
7. 16-Dec-2021
LIQUID FUEL
CONTAMINATIONS
• COURSE STRAINER OF 10 MESH SIZE FOR RAGS,
COTTON WASTE, LOOSE NUT-BOLTS, SCREWS
ETC AT ENTRY PIPE TO STORAGE TANK
• 40 MESH STRAINER BETWEEN SERVICE TANK
AND PREHEATERS
• 100 MESH BETWEEN HEATER AND BURNER
RECOMENDED STRAINER SIZES TO CHECK
CONTAMINATIONS
7
Manohar Tatwawadi
8. 16-Dec-2021
SOLID FUEL (COAL)
GRADATION BASED ON CALORIFIC VALUE
A Exceeding 6200 Kcal/kg
B 5600 – 6200
C 4940 – 5600
D 4200 – 4940
E 3360 – 4200
F 2400 – 3360
G 1300 – 2400
All figures in Kcal/kg
8
Manohar Tatwawadi
10. 16-Dec-2021
SIGNIFICANCE OF
PARAMETERS
FIXED CARBON:- SOLID FUEL LEFT IN THE FURNACE
AFTER VOLATILE MATTER IS DISTILLED OFF
VOLATILE MATTER:- METHANE, HYDROCARBONS,
HYDROGEN AND CO. (INDEX OF GASSIOUS FUELS
PRESENT)
• INCREASES FLAME LENGTH AND HELPS IN EASIER
INGITION OF COAL
• SETS MINIUM LIMIT ON FURNACE HEIGHT AND VOL.
• INFLUENCE SECONDARY AIR AND ITS DISTRIBUTION
• INFLUENCE SECONDARY OIL SUPPORT
10
Manohar Tatwawadi
12. 16-Dec-2021
SIGNIFICANCE OF
PARAMETERS
MOISTURE CONTENT:-
• REDUCES THE HEAT CONTENT PER KG OF COAL
• INCREASES HEAT LOSS DUE TO EVAPORATION
AND SUPERHEATING OF VAPOUR
• HELPS IN BINDING FINES
• AIDS RADIATION HEAT TRANSFER
12
Manohar Tatwawadi
13. 16-Dec-2021
SIGNIFICANCE OF
PARAMETERS
SULPHUR CONTENT:- 0.5% TO 0.8%
• AFFECTS CLINKERING AND SLAGGING
TENDENCIES
• CORRODES CHIMNEY AND OTHER
EQUIPMENT (A/H, ECNOMISER ETC)
• LIMITS EXIT FLUE GAS TEMP.
13
Manohar Tatwawadi
14. ANALYSIS OF COAL
PROXIMATE ANALYSIS PROCESS
1. Grinding coal to fine powder and weighing
2. Drying coal in atmosphere and weighing
3. Drying the coal in Nitrogen Furnace at 1100C
for one hour and weighing
4. Further subjected to 9250C for 7 minutes in
the Nitrogen furnace and weighing.
5. Further Burning the coal totally with oxygen
in the furnace to Ash and weighing (1.5 Hour)
6. Noting down the Proximate Analysis
16-Dec-2021 Manohar Tatwawadi 14
15. PROXIMATE ANALYSIS OF
COAL
• The difference of weight between 1 & 3
(the powdered coal and after drying the coal
in Nitrogen furnace to 1200C) gives the
moisture present in the coal. M.
• The difference of weight between 3 & 4
(Dried coal and the subjecting it to 9250C)
in Nitrogen Furnace gives the weight of the
volatile matter in the coal. VM.
16-Dec-2021 Manohar Tatwawadi 15
16. PROXIMATE ANALYSIS OF
COAL
• Ash in Coal denoted by A is given by the
weight at 5
• Further The difference of weights 4 & 5
gives us the Fixed Carbon in Coal denoted
by C for the calculations of Ultimate
Analysis.
• The procedures may slightly differ from
place to place but generally carried out as
per ASTM 3
16-Dec-2021 Manohar Tatwawadi 16
17. 16-Dec-2021
ULTIMATE ANALYSIS OF COAL DERIVED
FROM PROXIMATE ANALYSIS
RELATIONSHIP BETWEEN PROXIMATE AND
ULTIMATE ANALYSIS
%C = 0.97C+ 0.7 (VM – 0.1 A) – M (0.6 – 0.01 M)
%H = 0.036C+0.086 (VM-0.1A) – 0.0035 M2 (1-0.02 M)
%N2= 2.10 - 0.020 VM
Where
C = % OF FIXED CARBON, A = % ASH
VM = % VOLATILE MATTER, M = % OF MOISTURE
17
Manohar Tatwawadi
18. 16-Dec-2021
ULTIMATE ANALYSIS OF COAL
TYPICAL VALUES OF ULTIMATE ANALYSIS OF COAL
PROPERTIES INDIAN COAL INDONE.COAL
Moisture 5.98% 9.43%
Mineral Matter(Ash) 38.63% 13.99%
Carbon 42.11% 58.96%
Hydrogen 2.76% 4.13%
Nitrogen 1.22% 1.02%
Sulphur 0.41% 0.56%
Oxygen 9.89% 11.88%
Gross Cal. Value 4000 Kcal/Kg 5500 Kcal/Kg
18
Manohar Tatwawadi
19. 16-Dec-2021
Comparison of Chemical
Composition of Various Fuels
Constituent Fuel oil Coal Natural gas
Carbon 84 41.11 74.00
Hydrogen 12 02.76 25.00
Sulphur 03 00.41 —
Oxygen 01 09.89 Trace
Nitrogen Trace 01.22 00.75
Ash Trace 38.63 ---
Water Trace 05.98 -----
19
Manohar Tatwawadi
20. 16-Dec-2021
Burning of Fuel
• Required rate of combustion is dependent on the
heat energy requirements.
• For 500 MW Boiler the rate of coal combustion
roughly is 300 Tons/ Hour at FULL LOAD.
• For 210 MW Boiler, the rate of coal combustion
is 140 Tons/ Hour at FULL LOAD.
• So, Combustion system is designed for
achieving this rate, that too within the optimum
furnace volume.
20
Manohar Tatwawadi
21. 16-Dec-2021
Combustion Definition
Combustion is the rapid oxidation of fuel
accompanied by the production of heat and light
Solid or Liquid fuels must be changed to gas before they burn.
Heat is required to change solids and liquids into gasses
Most of the air 79% is nitrogen.
Nitrogen reduces combustion efficiency by absorbing heat
from combustion and reduces the heat available for
transfer.
It increases the volume of combustion by products.
At high temp. may produce oxides of Nitrogen (Toxic
Pollutants NOx).
21
Manohar Tatwawadi
22. 16-Dec-2021
• Combustion takes place only when fuel is in
contact with Oxygen in air and sufficient ignition
energy is available.
• Intense radiation from the flame provides ignition
energy.
• Oxygen is available from Air supplied from
Primary air and secondary air system.
• Rate of combustion is decided by the rate at which
Oxygen from air combines with fuel particles.
HOW FUEL BURNS
22
Manohar Tatwawadi
23. 16-Dec-2021
Combustion System Design Issues
Combustion system is designed to obtain
• High rate of combustion carried out in a
limited furnace space.
• Minimum heat losses.
• Ease of operation and maintenance of the
combustion system.
• Safety of Men and Equipment.
• Controllability of the combustion process.
23
Manohar Tatwawadi
24. 16-Dec-2021
Conditions Prevailing In The Furnace
• Mixture of Flue gases, Fly ash, Coal and air
prevails in the furnace
• Due to this nature of gas mixture, probability of
Oxygen reaching coal particles is very small.
• By proper design, this probability is increased to
optimum level
• Maintaining the parameters to design values is
therefore of prime importance.
24
Manohar Tatwawadi
25. 16-Dec-2021
How Coal Burns In The Furnace
Combustible matter present in the fuel/coal is..
1. Volatile Matter
2. Solid Coal/Carbon particles.
Complete combustion takes place when Volatile
matter as well as Solid Carbon particles burn
completely.
Volatile matter contains Hydrogen, Ethane,
Methane, Water Vapor etc.
25
Manohar Tatwawadi
26. 16-Dec-2021
Burning of Volatile Matter
Coal Particle
traveling with
Primary air
Furnace
Coal particle
devoid of VM
is called soot
On entering furnace,
particle expands and
VM gets released
rapidly
VM mixes with
PA and burns
out.
26
Manohar Tatwawadi
27. 16-Dec-2021
• Primary air is consumed in combustion of Volatile Matter.
• Combustion of VM completes within first 40 to 50
milliseconds if primary air is able to mix with gaseous VM.
• Primary air flow rate must be such that it fulfills Oxygen
requirement for combustion of VM.
• Combustion of soot particles is slow as Oxygen from air do
not reach to the solid particles as readily as that of VM.
• Oxygen transport to soot particles is by diffusion.
Combustion Process
27
Manohar Tatwawadi
28. 16-Dec-2021
Diffusion is the process in which Oxygen in the air travels
towards soot particle because of Difference in Concentration.
Burning Soot
Particle
Boundary
Layer of
flue gases
Surrounding
Bulk made of
Mixture of Air
+ Flue Gases
+ Ash
particles
Low O2 concentration
Bulk gas stream having
High O2 Concentration
28
Manohar Tatwawadi
29. 16-Dec-2021
Diffusion Coefficient is directly
proportional to concentration of
Oxygen in surrounding gases and
inversely proportional to Particle
Diameter.
29
Manohar Tatwawadi
Diffusion Coefficient
31. 16-Dec-2021
Rate of Diffusion = (Concentration of Oxygen in
Boundary layer of gases at the surface of burning coal
particle - Concentration of Oxygen in Bulk Gases present
in the furnace).
Ultimately The concentration of
Oxygen in furnace and the Particle
size are the controlling factors of
perfect combustion .
Perfect Combustion
31
Manohar Tatwawadi
32. 16-Dec-2021
A homogeneous mixture of all the gases in the
furnace is the most important design requirements.
Homogeneous Mixture ensures that
1. Coal particles remain surrounded by air mass
sufficient for its complete combustion.
2. High Oxygen concentration in the surrounding
air and low Oxygen concentration in the
boundary layer causes high diffusion rate.
Requirements for complete
combustion
32
Manohar Tatwawadi
33. 16-Dec-2021
Requirements for Complete
Combustion
• Mass of Air required for complete combustion depends on
mass of fuel particle.
• Furnace volume is selected such that 75 Micron size
particles (200 Mesh) can get sufficient Mass of Air for
complete combustion
• If particle size is more, it will get starved of air and hence
will not burn completely
• Resident time in Corner fired furnaces is 1 to 2 seconds
and all the particles should burn before reaching the
furnace neck.
33
Manohar Tatwawadi
34. 16-Dec-2021
• Admission of air from wind box in to furnace
only from Auxiliary air dampers
• Admission of combustion air only from the
Coal air dampers at elevations A,B,C,D,E and F
• Equal Opening of dampers at 4 corners of the
elevation.
How homogenous mixture is
ensured (Corner Fired Boilers)
34
Manohar Tatwawadi
35. 16-Dec-2021
Principles of Combustion
Carbon, Hydrogen and Sulphur in the fuel
combine with oxygen to form oxides
HEAT RELEASED BY COMBUSTION OF CONSTITUENTS
C + O2 ---- CO2 + 8084 KCAL/KG OF CARBON
2C + O2 ---- 2CO + 2430 KCAL/KG OF CARBON
2H2 + O2 -----2H2O + 28922 KCAL/KG OF HYDROGEN
S + O2 ----- SO2 + 2224 KCAL/KG OF SULPHUR
EACH KG OF CO FORMED MEANS A LOSS OF 5654 KCAL
OF HEAT (8084 – 2340)
35
Manohar Tatwawadi
36. 16-Dec-2021
3 T’s of Good Combustion
The objective of good combustion is to release
all of the heat in the fuel. This is accomplished
by controlling the “three T’s” of combustion
which are:-
(1)Temperature high enough to ignite and
maintain ignition of the fuel.
(2)Turbulence or intimate mixing of the fuel
and oxygen, and
(3)Time sufficient for complete combustion.
36
Manohar Tatwawadi
37. 16-Dec-2021
Good Combustion
Too much, or too little fuel with the available combustion air
may potentially result in unburned fuel and carbon
monoxide generation. A very specific amount of O2 is
needed for perfect combustion and some additional
(excess) air is required for ensuring complete combustion.
However, too much excess air will result in heat and
efficiency losses.
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Manohar Tatwawadi
38. 16-Dec-2021
• Dampers A,B,C,D,E,F open from 0 to 40% for 0%
to 100% loading of the coal mill.
• Dampers should be closed for the elevations not in
service.
• AB, CD, EF dampers open as per the oil pressure for
the elevation in service.
• For the elevations not in service, these dampers open
to maintain Furnace - Windbox DP.
• AA, FF, BC and DE dampers open to maintain
Furnace - Windbox DP
Auxiliary air dampers
(Secondary Air)
38
Manohar Tatwawadi
39. 16-Dec-2021
Air Requirement For Complete
Combustion of Coal
Calculation of Theoretical Air requirement
SAMPLE CASE :-
Molecular weights of different elements involved…..
Element Mol.Wt Compound Mol.Wt
Carbon (C) 12 CO2 44
Oxygen (O2) 32 SO2 64
Hydrogen(H2) 02 H2O 18
Sulphur(S) 32
Nitrogen(N2) 28
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Manohar Tatwawadi
40. Chemical Reactions and Fuel
Contents Analysis
Chemical reactions Fuel contents analysis
• C + O2 = CO2 Carbon in fuel = 42.11%
• H2 + ½ O2 = H2O Hydrogen = 2.76%
• S + O2 = SO2 Sulphur = 0.41%
16-Dec-2021 Manohar Tatwawadi 40
41. Combustion Process Analysis
• 12 Kg carbon will require 32 kg of oxygen to form 44 kg CO2
• 1 kg of carbon requires 32/12 = 2.67 kg of Oxygen
• 42.11kg of carbon will require 42.11*2.67 = 112.43kg of oxygen
• 4 kg of hydrogen will require 32kg of oxygen to form 36kg H2O
• 1 Kg Hydrogen requires 8 kg of oxygen
• 2.76 kg of hydrogen will require 2.76*8 = 22.08 kg of oxygen
• 1 kg of sulphur requires 1 kg of oxygen.
• 0.41 kg of sulphur will require 0.41 kg of oxygen
16-Dec-2021 Manohar Tatwawadi 41
42. 16-Dec-2021
Total oxygen required for complete combustion
= 112.43kg + 22.08 kg + 0.41 kg = 134.92kg of oxygen
Oxygen present in fuel = 9.89%
Extra oxygen required for combustion
= 134.92 – 09.89 =125.03 kg
Quantity of dry air required (air contains 23% oxygen by wt)
= 125.03/0.23 = 543.60 kg per 100 kg of fuel
Theoretical CO2% by volume
C + O2 = CO2 C= 42.11
42.11C+42.11*2.67O2 =154.53 CO2
Moles of CO2 in flue gas = 154.53/44 =3.512 moles
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Manohar Tatwawadi
43. 16-Dec-2021
Nitrogen in flue gas= 543.60 kg - 125.03 kg =418.57 Kg
Moles of N2 in flue gas = 418.57/28 = 14.94 moles
SO2 in flue gas = 0.5 S + 0.5*1O2 = 1 SO2 = 1Kg
Moles of SO2 in flue gas = 1/64 =0.016 moles
Total moles dry = 3.512 + 14.94 + 0.016 = 18.468 moles
Theoretical CO2% by volume =
Moles of CO2
Total Moles dry
X 100
= (3.512/18.468)X100
= 19.01% by volume
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Manohar Tatwawadi
44. 16-Dec-2021
CO2 with Excess air
Measured CO2% in flue gas = 15% (Sample Case)
Theoretical CO2 %
Actual CO2 %
Then Excess Air % = -1 X 100
19.01
15
- 1 X 100
= = 26%
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Manohar Tatwawadi
45. 16-Dec-2021
O2 with excess air & air ingress
Measured O2% at APH in = 3.8%
% Excess Air =
21
21- Measured O2
- 1 X 100
21
21- 3.8
- 1 X 100 = 22.09 %
% Air Ingrace in APH =
Measured O2% at APH in = 3.8% and APH out= 5.2%
O2 out – O2 in
21 - O2 out
X 100
% Air Ingrace in APH =
5.2% – 3.8%
21% - 5.2%
X 100 = 8.86 %
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Manohar Tatwawadi