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Considering economic and environmental issues, boosting renewable energy source is the main subject to fulfill energy demand in these days. Biomass as natural and abundant energy source can be typically used to produce electricity, fuels and heat applying thermochemical conversion processes such as combustion, pyrolysis or gasification. Biomass combustion is the most common process to produce electricity and useful heat in Turkey and all over the world. The aim of this study is to investigate the considerable influence of heating rates on combustion characteristics and kinetics employing a new developed non-linear kinetic model for hazelnut husk samples through thermogravimetric analysis. Furthermore, this work comprehensively assesses the variations in the reactivity of hazelnut husk combustion, expressed from thermogravimetric curves. The non-linear kinetic model developed in this study integrates the various kinetic pathway to estimate the major controlling parameter of combustion reactivity, its activation energy, pre-exponential factor and reaction order. According to comparison of results from the non-linear kinetic model for volatile combustion and fixed carbon combustion, correlation coefficients (R²) for both models are higher than 0.9985. These results proved the non-linear regression model for kinetic pathways in combustion reactivity worked properly to estimate thermal decomposition behavior. [ABSTRACT FROM AUTHOR]

In situ combustion is one of the oldest enhanced oil recovery methods usually applied to heavy oil fields to improve recovery. In this process, air or oxygen-enriched gas is injected into a reservoir, burning some of the oil in place and generating heat and combustion gases. A considerable fraction of heavy oil resources resides in naturally fractured systems. There is no reported successful application of in situ combustion in a field with fractured systems in the literature to date. There is a limited number of studies regarding the subject in the literature. Thus, fundamental understanding of the process in fractured systems is limited. In this study, laboratory experiments of in situ combustion in core samples with the presence of fractures were conducted. A total of 12 combustion tube experiments were conducted with 12° API heavy oil from the Bati Raman field in Turkey. These experiments differ in their configuration of fractures and oxygen concentration in the injected gas. Based on our experimental observations three distinct behaviors were observed regarding front propagation through fractured systems. The first type is strictly diffusion-limited, the second type is characterized by a thick combustion front and the last is homogenous behavior. These observations could provide a fundamental basis for possible field applications of in situ combustion in fractured systems. • Three distinct combustion front behaviors are observed. • An intermitted or continuous front could propagate in the fracture. • Recovery factors are lower in fractured systems. • O 2 concentration in the injected gas is key for success in fractured systems. • The presence of fractures promoted combustion front initiation. [ABSTRACT FROM AUTHOR]

In this study, the proximate analyses, such as volatile materials (VM), fixed carbon (FC), and higher heating value (HHV), were determined for 20 lignite samples from different areas of Turkey. The lignite samples have been tested with particle size of 0-0.05 mm. Combustion heats (higher heating values, HHVs) of 20 lignite samples obtained from different Turkish sources were determined experimentally and calculated from both ultimate and proximate analyses. The HHVs (MJ/kg) of the lignite samples as a function of fixed carbon (FC, wt%) or volatile materials (VM, %) was calculated from the following equations: [image omitted] [image omitted] The correlation coefficients for Eqs. (1) and (2) were 0.9820 and 0.9686, respectively. The combustion heats calculated from Eqs. (1) and (2) showed mean differences of +0.4% and +0.4%, respectively. [ABSTRACT FROM AUTHOR]

In this study, in order to determine atmospheric PAH concentrations in Inegol/Turkey, ambient air samples were collected from two different sites representing industrial and uncontrolled furniture manufacturers regions. Sampling campaign took place between December 2017 and November 2018. Air samples were collected using high volume air samplers (HVAS) and PAH concentrations were determined in both gas and particulate phases. The mean of the atmospheric PAH concentrations obtained in the gas phase in the furniture workshops (FW) and industrial district (ID) regions were 697.82 ± 637 ng/m3 and 772.92 ± 864.23 ng/m3, respectively. The concentrations in the particulate phase in the regions were 413.52 ± 430.23 ng/m3 and 342.40 ± 527.48 ng/m3, respectively. The average total (gas + particlulate phases) concentration of ∑ 16 PAH determined in the site of FW was 1111.34 ± 1045.24 ng/m3 while that was 772.92 ± 864.23 ng/m3 in ID. These values are over the ambient levels reported for urban sites wherein big industries exist around the world. Additionally, the average of particle phase percentage was 30% because of nearby combustion sources. The determination of possible sources of PAHs in the regions was performed using principal component analysis (PCA). PCA results showed that the main sources of pollutants of the regions are intertwined (combustion, traffic, industries). However, the most effective source is thought to be uncontrolled combustion of furniture wastes as fuel for residential heating. Health risks for the citizens were calculated for both regions and were found not to be at high-class risk. Image 1 • The total (gas + particulate phase) atmospheric PAH levels were determined much higher than the ones reported for urban areas. • The particulate phase percentage (30%) of PAHs were greater than most common range of 5–15%. • Uncontrolled hardboard and furniture waste combustion for heating purpose leads to elevated concentrations of PAHs in atmosphere. • PAH emissions sourced from traffic load, industrial emissions and contaminated wood combustion were intertwined. Gas/Particle concentrations of polycyclic aromatic hydrocarbons (PAHs) in ambient air of wooden industrial city in Turkey. [ABSTRACT FROM AUTHOR]