1. Major Components of Coal Fired Steam Generator System
Crushed to small pieces of about 20 mm diameter
~600mm
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2. Know Your Fuel Before You Know Your SG
Mostly Fossil Fules
Coal : Petroleum : Natural Gas

3. STUDY of COALIFICATION
P M V Subbarao
Professor
Mechanical Engineering Department
An Extremely Slow Action in Nature...
True Quasi-static Process to Create Permanent Entropy Vehicles…..

4. Coal : First Kind of Entropy Vehicle

5. Timing of Newton’s Law???

6. A tree converts disorder to order with a little help from the Sun
The building materials are in a highly disordered state - gases, liquids and vapors.
The tree takes in carbon dioxide from the air, water from the earth as well as a small amount from water vapor in the air.
From this disordered beginning, it produces the highly ordered and highly constrained sugar molecules, like glucose.
The radiant energy from the Sun gets transferred to the bond energies of the carbons and the other atoms in the glucose molecule.
In addition to making the sugars, the plants also release oxygen which is essential for animal life.

7. First Law Analysis of Photosynthesis : SSSF
m CO2
m water
m vegetation Q W
m Oxygen
The Global Reaction Equation:
Conservation of Mass:
First Laws for furnace in SSSF Mode:

8. Coalification
Orgin of Coal : A complex mixture of plant substances altered in varying degree by physical and chemical process.
Reaction time : ~~ 365 million years.
Mechanism of Formation:
In Situ Theory : Coal seam occupies the same site where original plants grew and accumulated.
Drift Theory : Plants and trees were uprooted and drifted by rivers to lakes and estuaries to get deposited.
During the course of time they got buried underground. Indian coals are formed according to drift theory.

9. In Situ Theory
Carboniferous periods of the Paleozoic when these areas were covered with forests
The humid climate of the Carboniferous Period (360 to 286 million years ago), which favoured the growth of huge tropical seed ferns and giant nonflowering trees, created the vast swamp areas

10. Sequence of Actions in Coalification
Dead Organic Matter
Living Plants & Trees
Bio-Chemical
Degradation of
Organic Material
Thermo-chemical
Conversion

11. Bio - Chemical Degradation of Dead Plants
As the plants died and fell into the boggy waters.
These Boggy waters excluded sufficient oxygen.
Bacteria could only partially decomposed but did not rot away the dead plants.
The absence of oxygen killed the bacteria.
The vegetation was changed into peat, some of which was brown and spongy, some black and compact, depending on the degree of decomposition.
Peat deposition is the first step in the formation of coal.

12. Formation of Peat Natural Rate of reaction : 3cm layer per 100 years.
Light brown fibrous at the surface and colour becomes darker with depth.
Typical Composition: Moisture : 85%, Volatile Matter : 8 %, Fixed Carbon : 4%, Ash : 3%.
Calorifica Value : ~2730 kJ/kg.
Occurrence of Peat : Nilgiri Hills and banks of Hooghly.
Sun dried Peat is very useful as a fuel with following composition:
Moisture : 20%, Volatile Matter : 50 %, Fixed Carbon : 25%, Ash : 5%
Bulk density : 300 kg/m3 and low furnace temperature and efficiency.
Products from Peat: Charcoal, Producer gas.

13. First Law Analysis of Formation of Peat :SSSF
m CO2
m vegetation Q
m Peat
m CH4
Species Conservation Equation:
Conservation of Mass:
First Laws for furnace in SSSF Mode:

14. Steps in Formation of Coal
Plant Debris
Peat
Lignite
Brown Coal
Diamond
Semi Anthracite
Anthracite
Bituminous
Sub-Bituminous

15. Molecular Structure of Peat
Structure of smallest molecule:
Bio-chemical Reaction:

16. Atmospheric CO2 Concentration at Peat Bogs

17. First Law Analysis of Formation of Peat :SSSF
m CO2
m vegetation Q
m Peat
m CH4
Species Conservation Equation:
Conservation of Mass:
First Laws for furnace in SSSF Mode:

18. Secondary Transformation : Geo-Chemical Stage
The decayed vegetation was subjected to extreme temperature and crushing pressures.
It took several hundred million years to transform the soggy Peat into the solid mineral.
20 m of compacted vegetation was required to produce 1 m seam of coal.
This is called as coalification or coal forming.
The extent to which coalification has progressed determines the rank of coal.

19. Secondary Transformation : Geo-Chemical Stage

20. Modeling of Combustible Coalification
Peat to Enriched peat: (mostly due to heating)
Enriched peat to lignite: (mostly due to pressure &heating)
lignite to Sub-bituminous: (mostly due to pressure &heating)
Sub-bituminous to High volatile Bituminous:

21. Global Reaction Model for Coalification
The application of basic kinetics to the real coalification requires some algebraic manipulations

22. Modeling of High Rank Coalification
High Volatile Bituminous to Medium volatile Bituminous:
Medium Volatile Bituminous to Low volatile Bituminous:
Low Volatile Bituminous to semi Anthracite:
Semi Anthracite to Anthracite:

23. Chemical Structure of Coal

24. Composition of Coals
The natural constituents of coal can be divided into two groups:
(i) The organic fraction, which can be further subdivided into microscopically identifiable macerals.
(ii) The inorganic fraction, which is commonly identified as ash subsequent to combustion.
The organic fraction can be further subdivided on the basis of its rank or maturity.

25. Microscopic Structure of Coals
On the microscopic level, coal is made up of organic particles called macerals.
Macerals are the altered remains and byproducts of the original plant material from which the coal-forming peat originated.
Macerals are to coal as sediment grains.
Coal petrographers separate macerals into three groups, each of which includes several maceral types.
The groups are Inertinite, Liptinite, and Vitrinite.
These groups were defined according to their grayness in reflected light under a microscope.

26. Parents of Microscopic Macerals.

27. Maceral Groups and Macerals in Coals

29. Origin of Maceral Groups
Vitrinite is thought to be derived mainly from the original woody tissue of trees in peat swamps.
Exinite , which is derived from pollen, spores and leaf epidermis, is technologically important, because it enhances the fluidity of coal.
The inertinite group of macerals derives its name from its more or less non-reactive character shown during the carbonization process.
Whereas exinite and vitrinite melt, with an evolution of volatiles, inertinites generally remain intact.
Inertinite is derived from fungal remains, charcoal and partly charred wood.

30. Chemistry of Maceral Groups
The maceral content and volatile-matter yield of a coal may be considerably influenced by the post-depositional chemical environment to which the normally acid peat is subjected.
There exist a correlation between carbon content and reflectance and this is used to precisely determine rank.
Petrographers in use the mean maximum reflectance of vitrinite in oil (Romax), at 546 µ, as the level of organic maturity, or rank, of a coal sample.

31. Carbon Content in Macerals

32. Vitrinite reflectance (Ro)
Vitrinite reflectance is the proportion of incident light reflected from a polished vitrinite surface.

33. Coal Reactivity
The reactivity parameter was calculated using the following equation:

34. Secrets of Coal Reactivity

35. Comprehensive Coal Characterization

36. Closing Remarks on Coal Knowledge
Reflectance Rank
0.50% % High-volatile bituminous
1.12% % Medium-volatile bituminous
1.51% % Low-volatile bituminous
1.92% - 2.5% Semi-anthracite
> 2.5% Anthracite

37. Natural Thermodynamics for Creation of Permanent of Entropy Vehicles

38. Chemical Structure of Combustible Coal

40. Coal Ranking vs Utilization

41. Mineral-Matter Composition of Coals
The ash of a coal is the uncombustible oxide residue which remains after combustion.
Mineral matter is the natural mineral assemblage of a coal that contains syngenetic, diagenetic and epigenetic species.
Mineral matter is identified more accurately by X-ray diffraction analysis of low-temperature ash (LTA).
The post-depositional chemical environment of a peat swamp, is the major factor determining the amount and kind of mineral species present in coal.

42. Analysis of Coal Proximate Analysis & Ultimate Analysis.
Proximate analysis - to determine the moisture, ash, volatiles matter and fixed carbon
Ultimate or elementary analysis - to determine the elemental composition of the coal
The Energy content -- CFRI Formulae --
Low Moisture Coal(M < 2% ) -- CV (Kcal/kg) = 71.7 FC (VM-0.1 A) - 60 M
High Moisture Coal(M > 2%) -- CV(kcal.kg) = 85.6 {100 - (1.1A+M)} - 60 M
Where, M, A, FC and VM denote moister, ash , fixed carbon and Volatile mater (all in percent), respectively.

43. Fuel Model

44. Dictionary of Few Indian Coals

45. Ash Model

46. Additional Characteristics of Coal
Sulfur Content : Coal with sulfur > 5% is not recommended for combustion.
Weatherability : Weathering or Slacking Index -- An indication of size stability -- Denotes the tendency to break on exposure to alternate wet and dry periods.
Grindability Index : A measure of relative ease of grinding coals or the power required for grinding coals in a pulverizer.
Burning Characteristics of Coal : Free burning coals and Caking Coals -- Caking index -- Pulverulent, sintered, weakly caked, caked and strongly caked.
Ash Fusion temperature -- The temperature where the ash becomes very plastic -- Design of ash handling system. -- Stoker furnace cannot use low ash fusion temperature coals.

47. Biochar Production Process

48. Biochar Production at IIT Delhi
Kiln Capacity:25 L, Efficiency:20-25% Feedstock: Leaf Waste, Operating Temperature<450° C

49. Analysis of Biochar Biochar samples C (%) H N S O O/C H/C Moisture
Volatile matter (%)
Fixed C (%)
Ash pH
LWB400
79.4
2.3
0.2
8.6
0.11
0.03
1.2
64.9
24.7
9.3
10.2
LWB300
71.3
3.1
0.9
0.5
12.6
0.18
0.04
1.6
67.5
20.3
10.6
9.8
LWB200
68.3
4.8
1.1
14.2
0.21
0.05
2.2
71.0
15.8
11.0
9.6

50. Maximum Extra-somatic Energy Content of A Fuel
Obtained only thru Combustion.
Standard heat of combustion:
The energy liberated when a substance X undergoes complete combustion, with excess oxygen at standard conditions (25°C and 1 bar).
The heat of combustion is utilised to quantify the performance of a fuel in combustion systems such as furnaces, Combustion engines and power plants.
In industrial terminology it is identified as the Gross Heating (calorific) Value or Higher Heating (calorific) value.
In a general design calculations, only Net Heating (calorific) Value or Lower Heating (calorific) value is used.

51. Measurement of Calorific Value : Bomb Calorimeter : Control Mass

52. Thermodynamic Description of Bomb Calorimeter
It is a combination of two closed systems.
Bomb: Constant volume closed system: Interacts only with calorimeter.
Calorimeter: Outer constant volume closed system:
Interacts only with bomb.
Isolates entire system with ambience.

53. The Bomb & Fuel

54. Temperature of Water in the Jacket

55. Energy Balance & Estimation of CV
Who all accepted the Thermal energy (heat) liberated due to combustion?