Engineering Journal (Faculty of Engineering, Chulalongkorn University, Bangkok)
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Optimization of Biochar Preparation from Acacia Wood for Soil Amendment
Get PDFAbstract. Biochar was prepared from Acacia wood by slow pyrolysis process under different conditions in order to determine the optimum condition of the pyrolysis temperature and time. The temperature was varied from 300 - 500oC meanwhile the time was varied from 1 - 3 hours. The regression analysis was applied to investigate the relationship between surface area, APD, and pH of biochar (response variables) and the independent factors (temperature and time). The response surface methodology was used for determining the optimum condition of biochar preparation from Acacia wood. The relationship between all response variables and the pyrolysis temperature and time is fit to the first order linear regression model. The pyrolysis temperatures have the significant impact (at 95% confident interval) on the surface area and APD of biochar meanwhile the pyrolysis times do not. The optimum condition for preparing biochar from Acacia wood using the laboratory electrical furnace is at 434.8oC, 1 hour of pyrolysis temperature and time. In addition, the proposed range of the optimum pyrolysis temperature is 413 – 450oC and the range of the optimum pyrolysis time is 1 – 2 hours.Biochar was prepared from Acacia wood by slow pyrolysis process under different conditions in order to determine the optimum condition of the pyrolysis temperature and time. The temperature was varied from 300 - 500oC meanwhile the time was varied from 1 - 3 hours. The regression analysis was applied to investigate the relationship between surface area, APD, and pH of biochar (response variables) and the independent factors (temperature and time). The response surface methodology was used for determining the optimum condition of biochar preparation from Acacia wood. The relationship between all response variables and the pyrolysis temperature and time is fit to the first order linear regression model. The pyrolysis temperatures have the significant impact (at 95% confident interval) on the surface area and APD of biochar meanwhile the pyrolysis times do not. The optimum condition for preparing biochar from Acacia wood using the laboratory electrical furnace is at 434.8oC, 1 hour of pyrolysis temperature and time. In addition, the proposed range of the optimum pyrolysis temperature is 413 - 450oC and the range of the optimum pyrolysis time is 1 - 2 hours
Reduction of DBP Precursors and Their THMFPs in Leachate Contaminated Groundwater by PAC Adsorption
Get PDFThis research investigated the reduction of dissolved organic matter (DOM) fractions and their trihalomethane formation potentials (THMFPs) by powder activated carbon (PAC) adsorption. Leachate contaminated groundwater around an inactive open-dumping landfill was selected as the raw water. The PAC adsorption reaction was proven to be the pseudo second order kinetic reaction and the Freundlich isotherm. The dissolved organic carbon (DOC), dissolved organic nitrogen (DON), and THMFP removals were 55%, 57%, and 73%, respectively. The hydrophobic (HPO) fraction exhibited a higher THMFP compared to the hydrophilic (HPI) fraction. The results of DOM fractionation show that the use of PAC adsorption produced an efficient 87% reduction of the HPO fraction, which is characterized as having a high reactivity toward THMFP
A New Activated Carbon Prepared from Sago Palm Bark through Physiochemical Activated Process with Zinc Chloride
Get PDFThis study aimed to use sago palm bark to formulate a new adsorbent activated carbon (AC) contains highly surface area through physicochemical method via ZnCl2 activation. Conduction of the activation process was performed at varying impregnation ratios (0.5 - 2.0). Thermal decomposition was determined using thermogravimetric analysis (TGA). Porosity characterizations of AC were conducted by using N2 adsorption-desorption in order to characterise properties like pore volume, surface area, and micropore volume. To detect the presence of functional groups which were found on the surface of AC, Fourier Transform Infrared Spectroscopy (FTIR) analysis was utilised. Morphology of AC was determined using scanning electron microscopy (SEM) and X-ray spectroscopy (EDX). Experimental results showed that maximum AC surface area was 1737 m2/g. Activation temperature was revealed to be 700oC, with chemical impregnation ratio of zinc chloride to a precursor equal to 1.5/1
Characteristics and Catalytic Properties of Ni/Ti-Si Composite Oxide Catalysts via CO2 Hydrogenation
Get PDFIn the present work, the effects of Ti addition on the characteristics and catalytic properties of the different silica-based supported nickel (Ni) catalysts were investigated. The different supports, such as the spherical silica particle (SSP), MCM41, TiSSP, and TiMCM were synthesized and used to prepare the Ni catalysts having 20 wt% of Ni loading for CO2 hydrogenation under methanation. The different supports and catalysts were characterized by means of N2 physorption, XRD, SEM/EDX, XPS, TPR, and CO chemisorption. The TiO2 was present in the anatase form after catalyst calcination. The addition of Ti can play important roles on the characteristics and catalytic properties of Ni catalysts by: (i) facilitating the reduction of Ni oxides species strongly interacted with support, (ii) preventing the formation of silicate compounds, and (iii) promoting the CO and CO2 dissociation resulting in complete inhibition of the reverse water-gas shift (RWGS) reaction, especially at high temperature. Based on CO2 hydrogenation, the NiTiMCM exhibited the highest activity and stability.In the present work, the effects of Ti addition on the characteristics and catalytic properties of the different silica-based supported nickel (Ni) catalysts were investigated. The different supports, such as the spherical silica particle (SSP), MCM41, TiSSP, and TiMCM were synthesized and used to prepare the Ni catalysts having 20 wt% of Ni loading for CO2 hydrogenation under methanation. The different supports and catalysts were characterized by means of N2 physorption, XRD, SEM/EDX, XPS, TPR, and CO chemisorption. The TiO2 was present in the anatase form after catalyst calcination. The addition of Ti can play important roles on the characteristics and catalytic properties of Ni catalysts by: (i) facilitating the reduction of Ni oxides species strongly interacted with support, (ii) preventing the formation of silicate compounds, and (iii) promoting the CO and CO2 dissociation resulting in complete inhibition of the reverse water-gas shift (RWGS) reaction, especially at high temperature. Based on CO2 hydrogenation, the NiTiMCM exhibited the highest activity and stability.  
Environmental Benefits of the Integrated Alternative Technologies of the Portland Cement Production: A Case Study in Thailand
Get PDFUnder the 2012-2050, the International Energy Agency (IEA) and the World Business Council for Sustainable Development (WBCSD) have developed a roadmap for the reduction of energy and carbon intensities in cement production. The aim of this research is to study and evaluate the energy consumption (EN), global warming potential (GWP) impact, and economic assessment of Portland cement production. It was found that the total EN and GWP of conventional process were 3.29 GJ per ton of Portland cement and 0.76 ton CO2 equivalent per ton of Portland cement, respectively. The total cost was 1,346 THB per ton of Portland cement. The largest contribution was from fossil fuels used and the limestone calcination in clinker production which produced the total EN of 83.63% and the total GWP of 91.36%, and the total cost of 63%. In addition, the production of Portland cement was environmentally improved by using low carbon fuels, increasing of alternative fuels to fossil fuels ratio, and increasing of pozzolan to cement ratio. The results showed that all improvements significantly reduce the total EN, GWP, and the total cost. When the using of low carbon fuels, the increasing of alternative fuels to fossil fuels ratio, and the increasing of pozzolan to cement ratio, the EN, GWP, and the total cost were decreased by 1.68%, 18.33%, and 4.39% of the total EN and by 25.35%, 3.06%, and 10.45% of the total GWP, and by 4.6%, 4.12%, and 10.64% of the total cost, respectively.Under the 2012 - 2050, the International Energy Agency (IEA) and the World Business Council for Sustainable Development (WBCSD) have developed a roadmap for the reduction of energy and carbon intensities in cement production. The aim of this research is to study and evaluate the energy consumption (EN), global warming potential (GWP) impact, and economic assessment of Portland cement production. It was found that the total EN and GWP of conventional process were 3.29 GJ per ton of Portland cement and 0.76 ton CO2 equivalent per ton of Portland cement, respectively. The total cost was 1,346 THB per ton of Portland cement. The largest contribution was from fossil fuels used and the limestone calcination in clinker production which produced the total EN of 83.63% and the total GWP of 91.36%, and the total cost of 63%. In addition, the production of Portland cement was environmentally improved by using low carbon fuels, increasing of alternative fuels to fossil fuels ratio, and increasing of pozzolan to cement ratio. The results showed that all improvements significantly reduce the total EN, GWP, and the total cost. When the using of low carbon fuels, the increasing of alternative fuels to fossil fuels ratio, and the increasing of pozzolan to cement ratio, the EN, GWP, and the total cost were decreased by 1.68%, 18.33%, and 4.39% of the total EN and by 25.35%, 3.06%, and 10.45% of the total GWP, and by 4.6%, 4.12%, and 10.64% of the total cost, respectively
Residual Strength of Composite Unprotected Steel-Deck Floor Exposed to High Temperature (Fire Flame)
Get PDFAn experimental programme was conducted to find out the behaviour of composite SB-RC deck floors fabricated from three secondary steel beams welded to another two main beams topped with a concrete slab, exposed to high temperature (fire flame) of 300, 500 and 700ºC for 1 hour, then allowed to cool down by leaving them at lab condition to return to ambient temperature. The burning results show that, by exposing them to a fire flame of up to 300ºC, no serious amount of permanent deflection can result. It was also seen that the middle and lateral secondary steel beams have recovered 92 and 95% of the deflection caused by heating, respectively. While the recovered deflection of burned composite SB-RC deck floor at 500ºC was 46 and 45%, respectively. The greatest deterioration was in the exposure to 700ºC, as this leads to a higher permanent deflection of the middle and the lateral secondary steel beams, and the recovery percentage was only 11 and 18%, respectively. Then all composite SB-RC deck floors loaded till failure to determine percentage decrease in ultimate capacity. The results were compared with the behaviour of composite SB-RC deck floor without burning (control specimen). The comparison shows that the pre-burned composite SB-RC deck floor at 300, 500 and 700ºC, gives a decrease in specimens’ stiffness compared with the unburned one, by about 17, 61 and 74% for the middle secondary steel beam, and 25, 62 and 75% for the lateral ones, respectively. Also, linearity behaviour of the load-deflection curve decreases as the burning temperature increased. It was 15, 61 and 75% comparing with the unburned specimen, respectively. Also, the residual ultimate strength capacity decreases as the burning temperature was increased. For the burned composite deck floors at 300, 500 and 700°C, it was 87, 64 and 38%, respectively, compared with the unburned specimen.An experimental programme was conducted to find out the behaviour of composite unprotected steel beam-reinforced concrete SB-RC deck floors fabricated from three secondary steel beams welded to another two main beams topped with a reinforced concrete slab, exposed to high temperature (fire flame) of 300, 500 and 700ºC for 1 hour, then allowed to cool down by leaving them at lab condition to return to ambient temperature. The burning results show that, by exposing them to a fire flame of up to 300ºC, no serious amount of permanent deflection can result. It was also seen that the middle and lateral secondary steel beams have recovered 92 and 95% of the deflection caused by heating, respectively. While the recovered deflection of burned composite SB-RC deck floor at 500ºC was 46 and 45%, respectively. The greatest deterioration was in the exposure to 700ºC, as this leads to a higher permanent deflection of the middle and the lateral secondary steel beams, and the recovery percentage was only 11 and 18%, respectively. Then all composite SB-RC deck floors loaded till failure to determine percentage decrease in ultimate capacity. The results were compared with the behaviour of composite SB-RC deck floor without burning (reference specimen). The comparison shows that the pre-burned composite SB-RC deck floor at 300, 500 and 700ºC, gives a decrease in specimens’ stiffness compared with the unburned one, by about 17, 61 and 74% for the middle secondary steel beam, and 25, 62 and 75% for the lateral ones, respectively. Likewise, linearity behaviour of the load-deflection curve decreases and the curves become flatter as the burning temperature increased. Also, the residual ultimate strength capacity decreases as the burning temperature was increased. For the burned composite deck floors at 300, 500 and 700°C, it was 87, 64 and 38%, respectively, compared with the unburned specimen
Adaptive Prioritized Probabilistic Caching Algorithm for Content Centric Networks
Get PDFThis paper presents an adaptive prioritized probabilistic caching algorithm (APP) for content centric networks (CCN). The objective of the new caching algorithm is to satisfy content requesters with both improving received data quality and maintaining overall network performance. APP allows CCN routers to cache data packets based on the caching probability which is prioritized and unequally handles incoming data packets according to data priorities. APP adjusts the caching probability based on cache events occurred at the CCN router, and the current caching probability is calculated from the previous caching probability. We evaluate APP performance via computer simulations and compare the performance of our caching algorithm with previous caching schemes. The performance evaluation metrics compose of the received data quality, cache-hit percentage, server load, and traffic load. The computer simulation results show that APP yields the better data quality to content requesters and nearly performs in-network caching as well as the previous probabilistic caching scheme
The Analysis and Control of Zero-Sequence Components in a Transformerless Back-To-Back (BTB) System Using Modular Multilevel Cascade Converters for Power Distribution Systems
Get PDFThis paper provides an intensive discussion on analysis and simulation of a back-to-back (BTB) system based on double-star chopper cells (MMCCs-DSCCs). It is installed between two 6.6-kV power distribution feeders. It is also referred to as the so-called “loop power flow controller.” A three-phase 200-V, 10-kW, 50-Hz BTB transformerless system is simulated to verify its operating principles, modelling, and performance of zero-sequence current control using combination between a simple PI controller and a common-mode choke. The simulation results show that the zero-sequence current circulating between the two feeders can be suppressed as small as 10 mA (0.03%) in rms, which is within acceptable value and small enough to negligible
Outdoor-Indoor Atmospheric Corrosion in a Coastal Wind Farm Located in a Tropical Island
Get PDFAtmospheric corrosion is important to consider for energy production and transmission. Important and valuable information have been accumulated in this subject; however, the application of new knowledge obtained is not completed. In order to contribute to a decrease in economic losses caused by atmospheric corrosion in wind farms, studies toward application of this knowledge should be carried out. One of the most common reasons for the failure of coastal structures and infrastructures is deterioration failure which is the result of structure deterioration and lack of project maintenance. Atmospheric corrosion was evaluated at outdoor and indoor exposure sites located at different distances from the sea in a wind farm region. Carbon and galvanized steel, copper and aluminum specimens were exposed. Main pollutants and atmospheric parameters were measured. Significant differences between outdoor corrosivity determined by dose response functions established on ISO standard respecting direct weight loss evaluation were found. Estimation carried out using dose response functions overestimate corrosivity (excepting copper). Main factors causing outdoor corrosion are different to indoor. Very high outdoor and indoor corrosivity classifications were determined.Atmospheric corrosion is important to consider for energy production and transmission. Important and valuable information have been accumulated in this subject; however, the application of new knowledge obtained is not completed. In order to contribute to a decrease in economic losses caused by atmospheric corrosion in wind farms, studies toward application of this knowledge should be carried out. One of the most common reasons for the failure of coastal structures and infrastructures is deterioration failure which is the result of structure deterioration and lack of project maintenance. Atmospheric corrosion was evaluated at outdoor and indoor exposure sites located at different distances from the sea in a wind farm region. Carbon and galvanized steel, copper and aluminum specimens were exposed. Main pollutants and atmospheric parameters were measured. Significant differences between outdoor corrosivity determined by dose response functions established on ISO standard respecting direct weight loss evaluation were found. Estimation carried out using dose response functions overestimate corrosivity (excepting copper). Main factors causing outdoor corrosion are different to indoor. Very high outdoor and indoor corrosivity classifications were determined
Preparation of Microcrystalline Cellulose from Waste Cotton Fabrics Using Gamma Irradiation
Get PDFRecycling process of waste cotton fabrics into value added products is still limited. Cotton fabrics are made of cotton fiber, which is a high cellulose source and it can be converted into microcrystalline cellulose (MCC). In this research, MCC was prepared by dissociation of waste cotton fabric using gamma irradiation with various radiation doses in dried phase and in wet phase by 35 % H2O2 solution. The properties of the prepared MCC were investigated and compared with standard Avicel PH101 MCC. The results from FTIR spectra and X-ray diffraction patterns show that the obtained MCC has typical similarity to commercial MCC. X-ray diffraction analysis showed that the crystallinity percentage (%Cr) was increased while crystallite size was decreased through gamma irradiation. At the same dose, degree of polymerization (DP) and solubility in water in dried phase, i.e. 135; 5.46 % were higher than wet phase irradiation i.e. 123; 4.38 %. Degree of polymerization and solubility in water decreases with increasing total irradiation dose. The investigated physicochemical properties of the obtained MCC conform to the European Pharmacopoeia requirements. The results indicated that waste cotton fabrics have a great potential as a low cost MCC raw material and can lead to many applications.Recycling process of waste cotton fabrics into value added products is still limited. Cotton fabrics are made of cotton fiber, which is a high cellulose source and it can be converted into microcrystalline cellulose (MCC). In this research, MCC was prepared by dissociation of waste cotton fabric using gamma irradiation with various radiation doses in dried phase and in wet phase by 35% H2O2 solution. The properties of the prepared MCC were investigated and compared with standard Avicel PH101 MCC. The results from FTIR spectra and X-ray diffraction patterns show that the obtained MCC has typical similarity to commercial MCC. X-ray diffraction analysis showed that the crystallinity percentage (%Cr) was increased while crystallite size was decreased through gamma irradiation. At the same dose, degree of polymerization (DP) and solubility in water in dried phase, i.e. 135; 5.46% were higher than wet phase irradiation i.e. 123; 4.38%. Degree of polymerization and solubility in water decreases with increasing total irradiation dose. The investigated physicochemical properties of the obtained MCC conform to the European Pharmacopoeia requirements. The results indicated that waste cotton fabrics have a great potential as a low cost MCC raw material and can lead to many applications