The influence of the combustion temperature of the non-volatile combustible wood matter of deciduous trees upon ash production and its properties

This paper presents the results of determining the influence of combustion temperature (500–1000 °C) of non-volatile wood matter of deciduous trees Aspen poplar (Populus Tremuloides Michx.), White birch(Betula verrucosa Ehrh.), European beech (Fagus Sylvatica L.), English oak (Quercus robur L.) and Black locust (Robinia pseudoacacia L.) upon the production of ash and the content of calcium Ca, magnesium Mg, potassium K and iron Fe. From the functional dependences between the influence of the combustion temperature of the non-volatile wood matter of the analysed wood species, it follows that the relative decrease in ash content at 1000 ºC compared with a burning temperature of 500°C is less for quaking Aspen poplar at ∆Ad= 44.1%, for the white birch at ∆Ad= 57.8%, for European beech at ∆Ad= 43.2%, for English oak at ∆Ad = 43.1% and for Black locust at ∆Ad= 34.2%.From determining the concentration of calcium Ca, magnesium Mg, potassium K in ash from the tree species using the ICP AES method, it follows that the highest proportion of ash for combustion temperature T = 500°C is in the range of calcium values XCa= 221.4–397.6 g·kg-1, magnesium in ash XMg = 25.7–42.3 g·kg-1, potassium XK= 130.5–199.8 g·kg-1and iron XFe= 1.78–2.88 g·kg-1. The influence of burning temperature is reflected in the increased concentration of calcium, magnesium and iron in ash and the decreased potassium concentrations in the ash. The decrease potassium in the ash is attributed to evaporation and potassium compounds found in non-volatile combustible of fuel wood.The decrease in potassium in the combustion process of non-volatile matter of fuel wood also affects the thermal characteristics of the produced ash and according to the criteria for the evaluation of biofuels from in terms of non-sintering ashes from biofuels (Ca + Mg) / K ≥1, contributes towards the stabilisation the creation of ash in crisp form.