Kinetic investigation on the smouldering combustion of boreal peat

Abstract

Advanced knowledge of the mechanisms and kinetic parameters controlling the thermal decomposition of peat is of importance for understanding smouldering peat fires and quantify fire risk. Smouldering fires not have the visual impact of the flaming front but constitute an important wildfire phenomenon because of the associated large carbon emissions and damage to a valuable ecosystem. Moreover, in case of extreme dry conditions or strong winds, smouldering fires develop easily into scrub or forest flaming fire. In this context, a thermal study on three different types of peat has been conducted: two high-moor peat types collected in Edinburgh (Scotland) and in Tomsk (Siberia), and one transition peat from Tomsk. The botanical composition, degree of decomposition and ultimate analysis were determined for the different samples and compared. These parameters were correlated to thermal behavior obtained by Thermogravimetry experiments. Significnalty different degradation behavior is observed for the different peat types. A kinetic method to predict the temperature of the sample at high heating rates is applied. Comparison shows a good correlation between experimental and numerical results.

Derivation of greenhouse gas emission factors for peatlands managed for extraction in the Republic of Ireland and the United Kingdom

“…(1) in Paton-Walsh et al, 2014). The C content of the peat (required for calculating EFs via the C mass balance approach) is assumed to be 53.3 %, as measured in Scottish Sphagnum moss peat (Cancellieri et al, 2012). For all other gas species considered in the study (CH 4 , ethylene (C 2 H 4 ) ethane (C 2 H 6 ), methanol (CH 3 OH), HCN, NH 3 ), we use their respective emission ratios to CO and the EF for CO to calculate EFs (via Eq.…”

Computational study of critical moisture and depth of burn in peat fires

“…The top layer has an MC lower than the critical value for ignition (MC t , MC* ig ) so it can be ignited by external heating. The middle layer (MC w ) is much wetter, and the bottom layer is air-dried peat, which is in equilibrium with the ambient MC b ¼ 10% (Cancellieri et al 2012;Huang and Rein 2014). The function of this dry layer is to create a consistent boundary and to minimise its influence on extinction and DOB.…”

“…The properties of a-char and b-char are assumed to be the same. The smouldering chemistry corresponding to the Scotland (SC) samples of subshrub and sphagnum high-moor peat (Rein et al 2008;Cancellieri et al 2012;Huang and Rein 2014) is selected for all three peat layers. Table 2 lists the kinetic and …”

“…The MC also increases with depth due to the proximity of the watertable. The average IC of the column is relatively high (IC ¼ 7:7%), so for simulations we use the decomposition chemistry of a Siberian scheuchzeria and sphagnum transition peat, IC SI-B E 8.8% (Cancellieri et al 2012), the kinetic parameters of which were found in Huang and Rein (2014 Fig . 10 shows the predicted evolutions of the temperature and moisture for the Oven Hol 2 sample.…”

“…For the low-mineral peat types (IC 4%), the smouldering chemistry of a Scotland subshrub and sphagnum high-moor peat, IC SC E 2% (Cancellieri et al 2012;Huang and Rein 2014) is used (see Table 2). For the high-mineral peat type (IC > 4%), the same Siberia (SI-B) peat as the Oven Hol 2 sample is used.…”