Nonisothermal Thermogravimetric Analysis of Thai Lignite with High CaO Content

Thermal behaviors and combustion kinetics of Thai lignite with different SO3-free CaO contents were investigated. Nonisothermal thermogravimetric method was carried out under oxygen environment at heating rates of 10, 30, and 50°C min−1 from ambient up to 1300°C. Flynn-Wall-Ozawa (FWO) and Kissinger-Akahira-Sunose (KAS) methods were adopted to estimate the apparent activation energy (E) for the thermal decomposition of these coals. Different thermal degradation behaviors were observed in lignites with low (14%) and high (42%) CaO content. Activation energy of the lignite combustion was found to vary with the conversion fraction. In comparison with the KAS method, higher E values were obtained by the FWO method for all conversions considered. High CaO lignite was observed to have higher activation energy than the low CaO coal

Performance and Thermoeconomic Analysis of a Biogas Engine Powered Ventilation System for Livestock Building

In this study, a biogas engine powered ventilation fan of a small swine farm was proposed. The research objective was to evaluate performance of, and apply a thermoeconomic analysis to an active ventilation system powered by a small biogas engine. Comparison was made against a gasoline engine and an electric motor. The engine used was a single-cylinder, four-stroke, spark ignited engine with capacity of 118 cm3. The biogas engine was found to be practically able to drive the ventilation fan with acceptable operation over a range of speeds and loads. At null price for biogas, the biogas engine proved to offer the lowest cost per product exergy unit at $0.054/MJ, which was considerably lower than the gasoline engine and electric motor

Predicting Ash Deposit Tendency in Thermal Utilization of Biomass

In thermochemical utilization of biomass, ash produced during the process is a major problem that can result in decreased performance and increased in difficulty during operation. Preliminary assessment of potential ash related troubles prior to the use of a specific biomass is valuable, even if it is only a general guideline. In this work, tendency of ash slagging, fouling and agglomeration in thermal processing of biomass was evaluated. Reference peered reviewed data including mineral content and fusion temperature of selected biomass ash were used to calculate multiple indicators (base to acid ratio, slagging index, fouling index, agglomeration index, slag viscosity index, and ternary diagram of main biomass ash composition) adopted from coal research. Major ash forming elements (Fe, Ca, Mg, K, Na, Al, Si) were found to be of relevance to ash melting and deposit behavior. For conventional biomass available locally, woody biomass (wood and wood sawdust) may be combusted without slagging or fouling problem, while non-woody biomasses (bark, husk, straw) are highly probable to experience some of these problems. The ash fusibility predictive models for woody and non-woody biomass were found to be effective. Mitigation can then be designed possibly via fuel blending to avoid or minimize the impact of biomass ash related trouble

Partial oxidation reforming of simulated biogas in gliding arc discharge system

Plasma assisted, partial oxidation reforming of biogas is considered to be a promising technology to produce synthesis gas. In this work, a 0.1 kW gliding arc plasma reformer was employed to investigate the effects of biogas composition and oxygen availability on CH4 and CO2 conversions, as well as the product distribution. Air was used in the partial oxidation of biogas. The results showed that at low CH4/O2 ratio or high oxygen availability, increasing CH4 content appeared to show higher H2 yield and CH4 conversion. Increasing CH4/O2 ratio adversely affected H2 and CO yields, and CH4 conversion. Optimum condition was found at CH4/CO2 of 90:10 and CH4/O2 of 1.2 for the maximum CH4 conversion and H2 yield of 45.7 and 25.3%, respectively

Energy-and Emission-Based Performance of an Experimental Tobacco Bulk-Curing Barn

ABSTRACT Energy conservation and efficiency of small tobacco curing industry in Northern Thailand was investigated. Traditional, flue-curing barn as well as a modern, bulk-curing, experimental barn were used as case studies. Firewood and lignite were used as fuels. The energy consumption, temperatures and CO, CO2 and O2 emissions were monitored during curing process. Performance analysis in terms of energy utilization index, thermal efficiency and emissions for both types of barn was carried out. The results indicated that the existing traditional rural barn consumed more energy and produced more emissions than the modern barn. This was largely due to greater energy loss through walls and ceiling of the barn and poorer combustion in a furnace. A new curing barn with improved energy efficiency and better emissions was demonstrated

Reaction Kinetics of Transesterification Between Palm Oil and Methanol under Subcritical Conditions

The objective of this work was to evaluate transesterification kinetics for biodiesel production from palm oil under subcritical conditions. Experimental investigation was carried out with palm oil and methanol at molar ratio of 46:1, temperatures between 150-200 °C and pressure around 140-190 atm in a 400 ml batch  reactor.  The biodiesel products were analyzed by gas chromatography – mass spectrometry. Area percentage method was used to estimate the methyl esters in the product. Zero- and first-order kinetic models were developed. Apparent activation energy was estimated to be in the range of 91-105 kJ/mol. The reaction rate equation was best approximated by the first order kinetic model with pre-exponential factor of 1.57 x 109.Key words: Biodiesel; Critical fluids; Kinetic equations; Methyl esters; Palm oil; Renewable energ

Gasification of Pelletized Corn Residues with Oxygen Enriched Air and Steam

This work studied generation of producer gas using oxygen-enriched air and steam mixture as gasifying medium. Corn residues consisting of cobs and stover were used as biomass feedstock. Both corn residues were pelletized and gasified separately with normal air, oxygen enriched air and steam mixture in a fixed bed reactor. Effects of oxygen concentration in enriched air (21-50%), equivalence ratio (0.15-0.35), and steam to biomass ratio (0-0.8) on the yield of product gas, the combustible gas composition such as H2, CO, and CH4, the lower heating value (LHV), and the gasification efficiency were investigated. It was found that the decrease in nitrogen dilution in oxygen enriched air increased proportion of combustible gas components, improved the LHV of producer gas, but gasification efficiency was not affected. The increase in equivalence ratio favoured high product gas yield but decreased combustible gas components and LHV. It was also observed that introduction of steam enhanced H2 production but excessive steam degraded fuel gas quality and decreased gasification efficiency. The highest gasification efficiency of each oxygen concentration was at equivalence ratio of 0.3 and steam to biomass ratio of 0.58 for cob, and 0.22 and 0.68 for stover, respectively

Forecasting arabica coffee yields by auto-regressive integrated moving average and machine learning approaches

Coffee is a major industrial crop that creates high economic value in Thailand and other countries worldwide. A lack of certainty in forecasting coffee production could lead to serious operation problems for business. Applying machine learning (ML) to coffee production is crucial since it can help in productivity prediction and increase prediction accuracy rate in response to customer demands. An ML technique of artificial neural network (ANN) model, and a statistical technique of autoregressive integrated moving average (ARIMA) model were adopted in this study to forecast arabica coffee yields. Six variable datasets were collected from 2004 to 2018, including cultivated areas, productivity zone, rainfalls, relative humidity and minimum and maximum temperatures, totaling 180 time-series data points. Their prediction performances were evaluated in terms of correlation coefficient (R2), and root means square error (RMSE). From this work, the ARIMA model was optimized using the fitting model of (p, d, q) amounted to 64 conditions through the Akaike information criteria arriving at (2, 1, 2). The ARIMA results showed that its R2 and RMSE were 0.7041 and 0.1348, respectively. Moreover, the R2 and RMSE of the ANN model were 0.9299 and 0.0642 by the Levenberg-Marquardt algorithm with TrainLM and LearnGDM training functions, two hidden layers and six processing elements. Both models were acceptable in forecasting the annual arabica coffee production, but the ANN model appeared to perform better

Bio-Oils From Vacuum Ablative Pyrolysis of Torrefied Tobacco Residues

Fast pyrolysis, in combination with torrefaction pretreatment, was used to convert tobacco residues to value-added bio-fuels and chemicals. Tobacco plant residues were torrefied at 220, 260, and 300 °C, before being pyrolyzed at 450, 500, 550, and 600 °C in a rotating blade ablative reactor under vacuum conditions to test the effects on product yields. With torrefaction, tobacco residues thermally decomposed 20-25% w/w at low temperatures. Torrefaction and pyrolysis temperatures were found to markedly affect pyrolytic product yields of bio-chars and bio-oils, while having no effect on gas-phase products. Bio-oil yields exhibited a direct relation with pyrolysis temperature and an inverse relation with torrefaction temperature. Bio-oils produced were separated into light and heavy oils and analyzed by GC-MS, and1H and13C NMR. Nicotine was found to be the main compound in the light and heavy oils along with several phenols and cresols in the heavy oil

Bio-Oils From Vacuum Ablative Pyrolysis of Torrefied Tobacco Residues

Fast pyrolysis, in combination with torrefaction pretreatment, was used to convert tobacco residues to value-added bio-fuels and chemicals. Tobacco plant residues were torrefied at 220, 260, and 300 °C, before being pyrolyzed at 450, 500, 550, and 600 °C in a rotating blade ablative reactor under vacuum conditions to test the effects on product yields. With torrefaction, tobacco residues thermally decomposed 20-25% w/w at low temperatures. Torrefaction and pyrolysis temperatures were found to markedly affect pyrolytic product yields of bio-chars and bio-oils, while having no effect on gas-phase products. Bio-oil yields exhibited a direct relation with pyrolysis temperature and an inverse relation with torrefaction temperature. Bio-oils produced were separated into light and heavy oils and analyzed by GC-MS, and1H and13C NMR. Nicotine was found to be the main compound in the light and heavy oils along with several phenols and cresols in the heavy oil