fuel ignition or self-heating · 2017. 5. 31. · thermal test for spon. comb. using...

Fuel Ignition or Self-heating

Prof. Ed Lester (PhD work from Claudio Avila and Niroj Mohalik)

Advanced Materials Research Group

Faculty of Engineering

University of Nottingham

ww.coalfire.caf.dlr.de

Worry now?

Previous work

First attempts

• Transport and storage losses

(Porter et al 1910, Parr 1911 & 1925, Beagle 1925)

• Trying to explain the phenomena

(Using adiabatic calorimeter, Davis et al 1925)

Some causes

• Sorption of oxygen (Carpenter 1966)

• Sorption of water (Davis 1926)

• Pyrites oxidation (only for high pyrites concentration)

(Graham 1923, Parr 1925, Sujanti 1999)

• Mechano-activation “Crushing increases surface area of coal” (Medek 2001)

• Bacterial action (Fuchs 1927, Coward 1957) finally refused

Mechanisms more relevant

• Influence of moisture (Hodges et al.1964, Bhattacharya 1971)

• Influence of oxygen (Hull et al 1995)

• Multi steps reaction mechanism “low and high temperature”

(Wang et al 2003)

Previous work

Recently works

• Some methods to predict Spon Comb created, such as: Crossing point temperature (Banerjee 1966, Feng 1973, Chen 1995) Deferential thermal analysis (Marinov 1977, Pis et al 1996)Adiabatic calorimeter (Davis 1925, Elder 1945, Gouws 1991)Self-heating rate test R70 index (Humphreys 1981)

Useful literature

• A Study of self-heating of fresh and oxidized coals by DTA.

Jose Pis and Fernando Rubiera, Incar Spain (Thermochemica acta V 279 (1996))

• On the prediction of thermal runaway of coal piles using a correlation between heath release and activation energy

Y. Nugroho, A. Mcintosh and Bernard Gibbs (Combustion Institute, V 28 (2000))

• Susceptibility to spontaneous combustion of Indian coals and lignites: an organic petrographic autopsy

B. Misra, B. Singh, India (Int. Journal of Coal Geology, V 25 (1994))

• Dimensional analysis: a magic art in fire research?

Philip Thomas, Bath UK (Fire Safety Journal, V 34 (2000))

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PKE 2

Sawdust 2

OLIVE CAKE 2

Cereal 2

Daw Mill 2

Thermal test for Spon. Comb. Using Thermogravimetric methods

15 coals have been used until now :- La Loma (Colombia, bituminous), Indo (Indonesia)- Bulli (Australia, Semi anthracite), Cynheidre (Wales, Anthracite), CWM (Wales, Semi Anthracite)- North Dakota (lignite), Illinois 6 (high volatile bituminous) , Pocahontas 3 (low volatile bituminous) {Argon premiumsamples from EEUU}- Cerrejon, Cerrejon seam 45 and Cerrejon seam 170 (Colombia, bituminous)- Fenosa (Indonesia) and Puertollano (Spain).

Specific work developed

Coal Water Volatiles Fix Carbon Ash

North Dakota 11.6 36.0 43.4 9.0

Illinois 6 2.7 39.6 41.8 15.9

Pocahontas 3 0.4 15.2 79.1 5.4

Cerrejon 3.7 37.7 53.5 5.1

C. Seam 45 2.6 37.1 57.1 3.2

C. Seam 170 4.8 39.4 54.3 1.6

La Loma 3.8 45.1 39.3 11.9

Indo 2.9 27.4 41.2 28.6

Fenosa (Indonesia) 10.8 41.7 44.4 3.2

Puertollano 0.6 22.1 25.8 51.5

Bulli 0.9 22.3 67.5 9.3

CWM 0.5 20.5 75.4 3.6


Introduction to Thermogravimetric analysis


- Sample is exposed to a ramp of temperature in a furnace- At the same time a balance measures the weight of the sample continuously

- Fenosa coal in a ramp of 10 degree per minute.


In temperature


We could repeat the same analysis using the graph related to temperature.


- Coals were exposed to different heating rates in air.- Slopes of the derivative curve were calculated at low temperature (almost linear).- We can use derivative curves in time or temperature having 2 different approaches:

In time



El Cerrejon N. Dakota

illinois Pocahontas



In time

Fenosa(high volatile)

La Loma

Indo Bulli(anthracite)

In time



In time



Slope

Position

Coef.

Stand.

dev.

0.1227 0.6939 0.9934

0.1036 0.5766 0.9901

0.0541 0.3658 0.985

0.0486 0.2981 0.9908

0.0416 0.3621 0.9922

0.0689 0.5036 0.9704

0.0675 0.4473 0.9861

0.0292 0.1649 0.9927

0.0165 0.1556 0.9747

The slope value is very important

North Dakota

Kaltim Prima

Pocahontas

Biomass and Coal together

Illustrative profile of the temperature in the surface of the sample

as a function of the furnace temperature (left), and the derivative

of the sample temperature as function of temperature (right).

Indian Coals Study

Research Background

Chasnalla Jitpur Enna Simlabahal Bhalgora

• Some cases crossing point temperature method produce misleading results.

• Limited research to explore a comprehensive comparative study

• No standard GHG measurement methodology from spontaneous heating of coal

http://www.sciencedirect.com/science/article/pii/S0166516211002011#gr7http://www.sciencedirect.com/science/article/pii/S0166516211002011#gr7

Fire Affected Area at Enna OCP, JCF

Microscope Mosaic Production

../bhp files/bhp training/Zeiss_imaging_system.mp4

Manual Analysis Automated Analysis

Sample Uv HCv ORv VRmo VRmo-m VRio VRio-i

1 10.0 10.4 79.6 1.05 0.31 0.76 0.23

2 15.2 10.0 74.8 0.92 0.16 1.01 0.35

3 4.8 5.2 90.0 0.91 0.04 0.74 0.24

4 23.0 20.4 53.6 1.04 0.07 0.87 0.2

5 27.2 6.4 66.4 1.02 0.02 0.91 0.14

6 17.2 10.4 72.4 1.04 0.02 0.96 0.05

7 33.6 9.2 57.2 1.02 -0.13 0.84 -0.06

8 26.8 12.8 60.4 0.95 -0.13 0.71 -0.09

9 49.6 16.0 34.4 1.03 -0.01 0.68 -0.2

10 48.0 5.6 46.4 1.08 0.03 1.04 0.04

11 26.0 10.0 64.0 1.1 0.01 0.8 0.03

A non coal self heating event - RDF

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Initial Fuel - Weight Loss at Fixed Temperatures

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Initial Fuel Slow Pyrolysis

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Fixed Temperature Oxidation Chute Samples

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Slow Pyrolysis Chute Sample

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Intrinsic Reactivity of Artificial Samples

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MALDI ToF Mass Spectrometer

•Analysis of molecular mass of complex mixtures

• Laser fired at sample to drive off molecules into a vacuum

Coal 1 Medium

Coal 9

Coal 3 Low/Medium

Coal 2 Low

Coal 7 High

Coal 8 Low

Original Fuel

Chute Deposit

Pile Sample

Simulated 300oC sample

Conclusions

• Some coals are naturally prone to self heating

• Moisture is a key issue – adsorption and release mechanisms generate heat

• Some coals/biomass can self-heat as a result of transport, storage or mine architecture

• Self heating is a complex set of mechanisms –both macro and micro

fuel ignition or self-heating · 2017. 5. 31. · thermal test for spon. comb. using...

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