The objective of the study was to investigate a more effective use of commercially available biomass pellets (wheat straw, wood, peat) using microwave pretreatment to improve heat production. Pellets were pretreated using the originally designed microwave torrefaction device. The effects of microwave (mw) pretreatment were quantified, providing measurements of the weight loss and elemental composition of pellets and estimating the effect of mw pretreatment on their porosity, surface area and calorific values at pretreatment temperatures of T = 448–553 K. Obtained results show that the highest structural variations and elemental composition during mw pretreatment were obtained for wheat straw pellets, with an increase in reactivity, a decreasing in the duration of the thermal decomposition by about 40% and an increase in the yield of combustible volatiles. Increased reactivity of pretreated pellets enhanced the ignition and burnout of volatiles, decreasing the duration of the burnout of pretreated wheat straw, wood and peat pellets by 40%, 24% and 9%, respectively, and increasing the peak and average values of the flame temperature, heat output, and produced heat energy by 40–50%, with a correlating increase of combustion efficiency and the mass fraction of carbon-neutral CO2 emission. Thus, the applicability of microwave pretreatment for the control and improvement of heat production was confirmed.

In the present study analysis of co-firing microwave (MW) pre-treated biomass pellets of different origins (wood and wheat straw), with raw pellets (wood, straw, and peat), to control and improve thermochemical conversion of biomass blends and achieve a sustainable use of local energy resources in energy production has been carried out. Effects of MW pre-treatment regimes and composition of blends were studied experimentally using measurements of the weight loss of blends, the yield of volatiles, flame temperature, total heat output from the device, and composition of products. It was found that co-firing MW pre-treated and raw biomass pellets promotes synergistic interaction between components of blends by increasing mass loss rate, the intensity of which depends on the proximate composition of pellets, MW pre-treatment regime and mass fraction of pre-treated pellets in the blend. The most effective synergistic interaction was found when co-firing pre-treated straw or wood pellets with raw peat, which increased the yield of combustible volatiles and heat output from the device as well as improved the composition of emissions. The least effective synergistic interaction was observed when co-firing pre-treated straw with raw wood pellets. Main factors that influenced the thermal and chemical conversion of MW pre-treated blends are discussed considering the effects of MW pre-treatment on the structural changes, elemental and chemical composition, and heating value of pre-treated pellets.

The aim of this study is to investigate the heat production and emissions of biomass blends consisting of commercial wood pellets and microwave (MW) pre-treated wheat straw pellets to intensify use of the straw in energy production. Three types of blends of wood and straw pellets with different pre-treatment conditions were used in this study. An experimental device consisting of a gasifier and combustor was used to analyse the effect of MW pre-treatment in blends on combustion characteristics: flame temperature, total heat power and product composition. The study revealed that MW pre-treatment of straw pellets enhances combustion characteristics of blends: faster thermal decomposition, increase of the flame temperature and combustion efficiency.

A wider use of the regional bioenergy resources for the development of environmentally friendly energy production providing microwave pretreatment of lignocellulosic biomass pellets (wood, straw, and peat) of different origin at a frequency of 2.45 GHz is promoted. A hypothesis is proposed and tested that microwave pretreatment of biomass pellets and blending of such pretreated pellets with raw pellets can be applied to enhance the thermochemical conversion of lignocellulosic biomass blends from different origin. The test results confirm that increased reactivity and heating value of pretreated biomass pellets enhances heat energy production and limits the formation of green house gases (GHG) emissions, thus advancing a more efficient usage of agricultural and forestry waste for energy production.

Titanium is widely used in specific applications due to its high strength, low density and good chemical stability. Despite it is one of the most abundant elements in the earth’s crust, it is very expensive, because production of pure metallic titanium is very complex. Kroll process is the way how most of the titanium is produced nowadays. Shortages of this process are that it is batch process and it is very energy exhaustive, because titanium sponge material after reduction reaction needs complex post processing to isolate pure titanium. In this work we describe and experimentally investigate technology for Ti production from titanium tetrachloride using combined Kroll and electroslag process. Such process allows to achieve better reaction product separation by molten slag and process can potentially be continuous, thus technological process to produce metallic titanium can be significantly shortened.