Inclination to self-ignition and analysis of gaseous products of wood chips heating

AbstractThis paper focuses on the assessment of the inclination to self-ignition of various types of wood chips according to the methodology of European standard EN 15188. The study also assesses the effect of heating temperatures on the composition and quantity of gaseous products of heating. Gases were analysed using an infrared spectrometer with Fourier transformation. From the measured results it was found that the inclination to self-ignition differs for various samples of wood chips. The paper discusses certain parameters assumed to affect the inclination of biomass to self-ignite. When assessing the effect of temperature on the composition of gaseous products, a sample of forest wood chips heated at temperatures from 50 to 150 °C resulted in the following gaseous products: carbon dioxide, carbon monoxide, water and aliphatic hydrocarbons; their concentrations increase with the increasing temperature. Carbon oxides have been proposed as indicators of the state of stored materials self-heating. Observations presented in this paper can be used as data for elaborating safety instructions for storage of fuels based on solid biomass.

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Assessment of the Moisture Effect on Gaseous Products of Self-Heating of Wood Chips

TRANSACTIONS of the VŠB – Technical University of Ostrava Safety Engineering Series ◽

10.1515/tvsbses-2017-0014 ◽

2017 ◽

Vol 12 (2) ◽

pp. 52-60 ◽

Cited By ~ 1

Author(s):

Hana Věžníková ◽

Michaela Perďochová ◽

Martina Uhrová

Keyword(s):

The Other ◽

Wood Chips ◽

Effect Of Temperature ◽

Gas Release ◽

Oxidation Reactions ◽

Moisture Effect ◽

Gaseous Products ◽

Self Heating ◽

The One ◽

Increasing Temperature

Abstract Biofuels are stored in large quantities and may be susceptible to self-ignition. The possible methods of indication of temperature increase include the analysis of the gaseous products of heating where concentrations of certain gases may increase with increasing temperature. Gas release is also affected by the moisture of the material given that the moisture level changes surface accessibility for oxygen on the one side and serves as a catalyst of the oxidation reactions on the other. The present project analysed the effect of temperature and moisture on gaseous products of heating of wood chips, one of frequently used biofuels, with the aim to determine a suitable gaseous indicator of beginning self-ignition.

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EFFECT OF TEMPERATURE ON NET CARBON DIOXIDE EXCHANGE RATES OF TWELVE BARLEY VARIETIES

Canadian Journal of Plant Science ◽

10.4141/cjps68-069 ◽

1968 ◽

Vol 48 (4) ◽

pp. 363-368 ◽

Cited By ~ 4

Author(s):

D. P. Ormrod ◽

W. F. Hubbard ◽

D. G. Faris

Keyword(s):

Carbon Dioxide ◽

Exchange Rates ◽

Effect Of Temperature ◽

Carbon Dioxide Exchange ◽

Controlled Environment ◽

Response Curves ◽

Gradual Decline ◽

Carbon Dioxide Uptake ◽

Higher Temperature ◽

Increasing Temperature

Seedlings of 12 barley varieties were grown in a controlled environment to 21 days of age and then transferred to an apparatus for measuring net carbon dioxide exchange rates. Rates were measured at temperatures ranging from 4 to 34 °C and the results were plotted to provide a response curve for each variety. The response curves were not clearly different between varieties, but some trends were evident. The varieties Husky, Parkland and Vantmore had response curves of similar shape with marked increases with increasing temperature to 14 to 18 °C. Asa, Olli and Pirkka showed a more gradual rise to about 20 °C. Varieties O.A.C. 21, Vantage and Wolfe showed a very rapid increase in carbon dioxide uptake to about 6 °C followed by very little change to 20 °C, leading into a gradual decline. Stavropol, Trebi and White Gatami had maximum rates at a higher temperature. The patterns presented by the varieties may be related to different areas of origin and production. Varieties were markedly different at low temperatures but differed little in response to temperatures near 34 °C. Absolute rates of net carbon dioxide exchange differed markedly among varieties.

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Kinetics of temperature-programmed reactivation of a hydrodesulphurization catalyst

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19833340 ◽

1983 ◽

Vol 48 (12) ◽

pp. 3340-3355 ◽

Cited By ~ 2

Author(s):

Pavel Fott ◽

Pavel Šebesta

Keyword(s):

Carbon Dioxide ◽

Thermal Analysis ◽

Differential Thermal Analysis ◽

Thin Layer ◽

Kinetic Parameters ◽

Diffusion Region ◽

Reaction Heat ◽

Gaseous Products ◽

Temperature Programmed ◽

Kinetics Of

The kinetic parameters of reactivation of a carbonized hydrodesulphurization (HDS) catalyst by air were evaluated from combined thermogravimetric (TG) and differential thermal analysis (DTA) data. In addition, the gaseous products leaving a temperature-programmed reactor with a thin layer of catalyst were analyzed chromatographically. Two exothermic processes were found to take part in the reactivation, and their kinetics were described by 1st order equations. In the first process (180-400 °C), sulphur in Co and Mo sulphides is oxidized to sulphur dioxide; in the second process (300-540 °C), in which the essential portion of heat is produced, the deposited carbon is oxidized to give predominantly carbon dioxide. If the reaction heat is not removed efficiently enough, ignition of the catalyst takes place, which is associated with a transition to the diffusion region. The application of the obtained kinetic parameters to modelling a temperature-programmed reactivation is illustrated on the case of a single particle.

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Theoretical Effect of Temperature on Threshold in the Hodgkin-Huxley Nerve Model

The Journal of General Physiology ◽

10.1085/jgp.49.5.989 ◽

1966 ◽

Vol 49 (5) ◽

pp. 989-1005 ◽

Cited By ~ 39

Author(s):

Richard Fitzhugh

Keyword(s):

Relaxation Time ◽

Relaxation Times ◽

Giant Axon ◽

Temperature Curve ◽

Effect Of Temperature ◽

Threshold Temperature ◽

Ionic Conductances ◽

And Shifts ◽

The Right ◽

Increasing Temperature

In the squid giant axon, Sjodin and Mullins (1958), using 1 msec duration pulses, found a decrease of threshold with increasing temperature, while Guttman (1962), using 100 msec pulses, found an increase. Both results are qualitatively predicted by the Hodgkin-Huxley model. The threshold vs. temperature curve varies so much with the assumptions made regarding the temperature-dependence of the membrane ionic conductances that quantitative comparison between theory and experiment is not yet possible. For very short pulses, increasing temperature has two effects. (1) At lower temperatures the decrease of relaxation time of Na activation (m) relative to the electrical (RC) relaxation time favors excitation and decreases threshold. (2) For higher temperatures, effect (1) saturates, but the decreasing relaxation times of Na inactivation (h) and K activation (n) factor accommodation and increased threshold. The result is a U-shaped threshold temperature curve. R. Guttman has obtained such U-shaped curves for 50 µsec pulses. Assuming higher ionic conductances decreases the electrical relaxation time and shifts the curve to the right along the temperature axis. Making the conductances increase with temperature flattens the curve. Using very long pulses favors effect (2) over (1) and makes threshold increase monotonically with temperature.

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