Devolatilisation kinetics and pyrolytic analyses were carried out on Tectona grandis (teak) using iso-conversional methods (Flynn-Wall-Ozawa and Starink) and analytical Py-GC/MS technique respectively. Proximate and elemental analyses were also performed and they showed that the ash and C contents and the HHV were 0.7%, 49.6% and 19.8MJ/kg respectively. Biomass sample was subjected to multiple heating rates (5-35K/min) in thermogravimetric experiments and kinetic parameters were evaluated from the non-isothermal TGA curves. The activation energy (E) varied between 222 and 300kJ/mol as a function of degree of conversion. Similarly, the pre-exponential frequency factor (A) varied between 9.6×10(17) and 9.55×10(24)min(-1). Analytical Py-GC/MS showed the presence of CO2, acetic acid, furan+2-butanone, levoglucosan, trans-coniferyl alcohol and lignin derivatives. The proportion of phenolic compounds identified was more than one-third with isoeugenol, acetoguaiacone, and 4-vinylguaiacol showing dominance.

The impact of torrefaction temperature on the ignitability, fuel ratio and ash fusion temperatures of two tropical deciduous woods (Teak and Melina) were investigated in a setup of tubular furnace. The properties considered are calorific value, fuel ratio, ignitability index, ash compositions and ash fusion temperatures of the biomass. Six different temperatures (220, 240, 260, 280, 300 and 320 C) at 60 min reaction time were considered. The results indicated that as torrefaction temperature increased, the calorific value, fuel ratio and ignitability index of the biomass also increased. The ignitability index of biomass (40-63) was better than the value (35) recommended for fuel applicable in thermal plants for power generation. The ash compositional analysis revealed that there was no variation in the quantity of SiO 2 , Al 2 O 3 , CaO along with other minerals for the raw and torrefied biomass. This implied that the temperature up to 320 C has no significant impact on the compositions of biomass ash during torrefaction. The ash fusion temperature test showed that the biomass ash softens at % 1200 C and finally fused at % 1300 C. The study concluded that an increase in torrefaction temperature increases the thermal properties of the torrefied biomass without affecting the compositions of biomass ash or lowering the ash fusion temperatures.

No abstract

Coal processing industries generate millions of tons of fines (<3 mm) during mining operation and are often considered as wastes. These wastes have enormous potential in serving as energy and metallurgical operation feedstock. One avenue for its use is densification into briquettes or pelletizes. Various briquetting techniques have been adopted in the past few decades; however, the main issues upfront in commercializing these techniques are significant binder cost and poor mechanical integrity. Therefore, the present study concentrates on utilizing commonly available organic binder along with pretreated biomass in developing coal fine briquettes. Briquettes were produced after initial pretreatment of the raw materials under a load of 2 tons. Briquettes were cured in an inert environment and eventually characterized for its main litmus requirements (physical properties). It was observed that pitch-molasses bonded briquettes have better physical properties leading to good mechanical integrity than briquettes produced from individual binder. The proximate, ultimate and calorific value analyses of the briquettes do not deteriorate but mildly improved compared to the raw coal fines. With a density of 1.18–1.32 g/cm 3 , drop to fracture that is greater than 100 (times/2 m), impact resistance index well above 6000, water resistance index of 99% and cold crushing strength of 9 MPa, pitch-molasses bonded briquettes clearly surpassed recommended physical properties benchmarked for briquettes of industrial and domestic end use. The physical properties of the briquettes favorably meet requirements as feedstock for rotary kiln direct reduced iron and COREX iron-making processes as well as fuel for thermal operations.

Torrefaction experiments were carried out on some Nigerian woody (Albizia pedicellaris (AP), Tectona grandis (TK), Terminalia ivorensis (TI)) and non-woody (Sorghum bicolour glume (SBG) and stalk (SBS)) biomass resources. The influence of process conditions and consequent change in the elemental configuration of the biomass samples were observed. Biomass type played a dominant role in the solid yield recording 71% for woody and 58% for non-woody samples at 270 • C, while temperature showed the greatest influence with solid yield dropping from an average of 80% (at 240 • C) to 50% (at 300 • C). Both volatile matter and fixed carbon contents experienced significant changes after torrefaction and a decline in O/C ratio from 0.6 to 0.3 was noted. Among the woody biomass, TI experienced the highest increase in higher heating value (HHV) of approximately 38% as compared to AP (32%) and TK (32%), and was subsequently selected for decomposition kinetic study. The decomposition kinetics showed that activation energy (E(˛)) for the hemicellulose degradation stage ranged between 137 and 197 kJ mol −1 for conversion (˛) between 0.1 and 0.24 implying that biomass kinetics within this decomposition region is a multi-step reaction. The GC/MS analytical technique revealed that the presence of levoglucosan was highest (7.1%) in woody biomass, while phenolic compounds made up more than one-third of the group of compounds identified.

Woody (Albizia pedicellaris and Terminalia ivorensis) and non-woody (guinea corn (Sorghum bicolor)) glume and stalk biomass resources from Nigeria were subjected to thermo-analytical and physico-chemical analyses to determine their suitability for thermochemical processing. They were found to have comparably high calorific values (between 16.4 and 20.1 MJ kg -1 ). The woody biomass had very low ash content (0.32%), while the non-woody biomass had relatively high ash content (7.54%). Thermogravimetric analysis (TGA) of the test samples showed significant variation in the decomposition behavior of the individual biomasses. Gas chromatography/mass spectrometry (GC/MS) of fatty acid methyl esters (FAMEs) derivatives indicated the presence of fatty and resin acids in the dichloromethane (CH2Cl2) extracts. Analytical pyrolysis (Py-GC/MS) of the samples revealed that the volatiles liberated consisted mostly of acids, alcohols, ketones, phenols, and sugar derivatives. These biomass types were deemed suitable for biofuel applications.

Your article is protected by copyright and all rights are held exclusively by Springer Science +Business Media Dordrecht. This e-offprint is for personal use only and shall not be selfarchived in electronic repositories. If you wish to self-archive your article, please use the accepted manuscript version for posting on your own website. You may further deposit the accepted manuscript version in any repository, provided it is only made publicly available 12 months after official publication or later and provided acknowledgement is given to the original source of publication and a link is inserted to the published article on Springer's website. The link must be accompanied by the following text: "The final publication is available at link.springer.com".

The evaluation of thermal decomposition characteristics and kinetic parameters of melina wood were investigated. Proximate, ultimate and calorific value analyses of the melina wood were carried out based on standards. Melina wood was subjected to multiple heating rates (5-15 C/min) in thermogravimetric experiment. Two prominent isoconversional methods (Flynn-Wall-Ozawa and Starink) were adopted to obtain kinetic parameters from the non-isothermal thermogravimetric analysis curves. The ash, volatile matter and carbon contents of the melina were 2.15, 81.42 and 47.05%, respectively, while the calorific value was 18.72 MJ/kg. The main devolatilization stage of melina ranged from 220 C to 350 C while 80% weight loss was obtained below 400 C. The activation energy varied between approximately 15 and 162 kJ/mol as a function of degree of conversion. The pre-exponential factors varied between 1.60E þ 2 and 5.67 E þ 12/min. The decomposition kinetic mechanism of melina is concluded to be a multi-step reaction.