Fuel Ignition or Self-heating

Transcription

1 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

2 ww.coalfire.caf.dlr.de

3 Worry now?

4 Worry now?

5 Worry now?

6 Worry now?

7 Worry now?

8 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)

9 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))

10 dw/dt PKE 2 Sawdust 2 OLIVE CAKE 2 Cereal 2 Daw Mill Temperature

11 Specific work developed 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 premium samples from EEUU} - Cerrejon, Cerrejon seam 45 and Cerrejon seam 170 (Colombia, bituminous) - Fenosa (Indonesia) and Puertollano (Spain). Coal Water Volatiles Fix Carbon Ash North Dakota Illinois Pocahontas Cerrejon C. Seam C. Seam La Loma Indo Fenosa (Indonesia) Puertollano Bulli CWM

12 Specific work developed Thermal test for Spon. Comb. Using Thermogravimetric methods 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.

13 Specific work developed Thermal test for Spon. Comb. Using Thermogravimetric methods In temperature We could repeat the same analysis using the graph related to temperature.

14 Thermal test for Spon. Comb. Using Thermogravimetric methods In time - 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:

15 Specific work developed Thermal test for Spon. Comb. El Cerrejon Using Thermogravimetric methods N. Dakota illinois Pocahontas

16 Specific work developed Thermal test for Spon. Comb. In time Using Thermogravimetric methods Fenosa (high volatile) La Loma Indo Bulli (anthracite)

17 Specific work developed Thermal test for Spon. Comb. Using Thermogravimetric methods In time

18 Specific work developed Thermal test for Spon. Comb. Using Thermogravimetric methods In time Slope Position Coef. Stand. dev The slope value is very important

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21 North Dakota

22 Kaltim Prima

23 Pocahontas

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26 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).

27 Indian Coals Study

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29 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

30 Fire Affected Area at Enna OCP, JCF

31 Microscope Mosaic Production

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34 Manual Analysis Automated Analysis Sample U v HC v OR v VR mo VR mo-m VR io VR io-i

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36 A non coal self heating event - RDF

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38 Weight (%) Initial Fuel - Weight Loss at Fixed Temperatures [150] [250] [350] [450] [550] [650] Time (mins)

39 dw/dt Initial Fuel - Intrinsic Reactivity Temperature ( o C)

40 dw/dt Initial Fuel Slow Pyrolysis Temperature ( o C)

41 Weight (%) 120 Fixed Temperature Oxidation Chute Samples [150] [250] [350] [450] [550] [650] Time (mins)

42 dw/dt 6 Intrinsic Reactivity Chute Sample Temperature (oc)

43 dw/dt Slow Pyrolysis Chute Sample Temperature (oc)

44 Weight (%) Fixed Temperature Runs Caked Sample [150] [250] [350] [450] [550] [650] Time (mins)

45 dw/dt Intrinsic Reactivity Caked Sample Temperature ( o C)

46 dw/dt Slow Pyrolysis Caked Sample Temperature ( o C)

47 dw/dt 14 Intrinsic Reactivity of Artificial Samples [200] [300] [400] [500] [600] Temperature ( o C)

48 6.00 Slow Pyrolysis of Artificial Samples 5.00 dw/dt 4.00 [200] [300] 3.00 [400] [500] [600] Temperature 600 (oc)

49 dw/dt Slow Pyrolysis Caked Sample [300] [400] 350 Theoretical Temperature ( o C)

50 dw/dt 8.00 Intrinsic Reactivity Caked Sample [300] [400] Temperature ( o C)

51 MALDI ToF Mass Spectrometer Analysis of molecular mass of complex mixtures Laser fired at sample to drive off molecules into a vacuum

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53 Coal 1 Medium Coal 9 Coal 3 Low/Medium Coal 2 Low Coal 7 High Coal 8 Low

54 Original Fuel

55 Chute Deposit

56 Pile Sample

57 Simulated 300 o C sample

58 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