Pyrolysis Kinetic Analysis of Biomasses: Sugarcane Residue, Corn Cob, Napier Grass and their Mixture

The aim of this study is to investigate pyrolysis kinetic parameters of three high potential energy biomasses including sugarcane residue (tops and leaves), corn cob and Napier grass via thermogravimetry analysis (TGA). In addition, those of their mixture at 1:1:1 by mass is explored. Activation energy and pre-exponential factor were the two considered parameters calculated by following the Ozawa-Flynn-Wall method using condition of 30-900°C with heating rates of 5, 10, 20 and 40°C/min. The derivative thermogravimetric (DTG) curves indicated that there might be at least three different component structures in corn cob. The effective values of the both parameters were almost similar as 214.54, 216.60, 212.51 kJ/mol and 1.510E+19, 1.575E+19, 1.562E+19 min-1 for the sugarcane residue, the corn cob, the Napier grass, respectively. Finally, the ternary diagram suggested that the increase of Napier grass proportion would slightly affect the conversion of pyrolysis by reducing the total activation energy of the biomass mixture

Synthesis of Na2WO4-Mn Supported YSZ as a Potential Anode Catalyst for Oxidative Coupling of Methane in SOFC Reactor

The oxidative coupling of methane (OCM) over a 5%Na2WO4-2%Mn on YSZ, has been investigated in a fixed bed reactor (FBR) and a solid oxide fuel cell reactor (SOFC). A 60% C2 selectivity and a 26% CH4 conversion have been obtained in a FBR at 800oC and CH4/O2 of 4 : 1. Importantly, an addition of Na2WO4-Mn to YSZ support can significantly enhance the performance of the catalyst especially C2 hydrocarbons selectivity and CH4 conversion. A maximum power density of 7.8 mW cm−2 was achieved at 800°C with CH4 in the SOFC reactor having a 50 μm thick YSZ electrolyte. The CH4 conversion and C2 selectivity at 800°C were 1.1% and 85.2%, respectively

Efficiency of Heat Transfer Improvement Performed in Circular Tubes Utilizing Various Types of Ring-Shaped Turbulators

The enhancement of heat transfer performance by using different types of ring-shaped turbulators equipped in a circular tube was investigated through 3D numerical simulations (CFD) with the finite volume method. Three types of turbulators—orbicular-ring turbulator (ORT), pyramidal-ring turbulator (PRT) and proposed innovative cogwheel-ring turbulator (CRT)—were considered. Air at 300 K was passed through the tube with uniform wall heat flux conditions varying from Reynold’s numbers of 4,000 to 20,000. The standard k-ε turbulence model was used to simulate the flows via the ANSYS FLUENT commercial software. Geometric influences in the heat transfer were investigated in terms of compositing the diameter ratio (DR = 0.5, 0.6 and 0.7), the pitch ratio (PR = 4 and 8) and the number of teeth in the cogwheel-ring turbulator (N = 6, 8 and 10). In conclusion, the heat transfer rate in the tubes fitted with ORT and PRT were in the range of 87, which was 199% higher than that of the tube without a turbulator. The PRT offered a slightly higher heat transfer rate than the ORT. Decreasing the pitch and diameter ratio could increase the heat transfer rate. Moreover, it was demonstrated that the proposed innovative CRT outperformed both the ORT and PRT in terms of heat transfer performance. In the case of CRT, the highest number of teeth (N) offered the lowest friction factor and pressure drop

System Efficiency Analysis of SOFC Coupling with Air, Mixed Air-Steam and Steam Gasification Fueled by Thailand Rice Husk

In this work, integrative biomass gasification with solid oxide fuel cell (SOFC) system using rice husk as feedstock was studied under various operations. It was found that the stand-alone mixed air-steam gasification provided significant higher benefit than alone air and steam gasification. The mathematical model was developed to predict the electrical, thermal and overall efficiency of the system. It was found that the SOFC with steam gasification also provided the greatest overall efficiency of 96%. Hence, the steam gasification is a promising option for coupling with SOFC to generate electricity from biomass

Two-Dimensional Modeling of the Oxidative Coupling of Methane in a Fixed Bed Reactor: A Comparison among Different Catalysts

A proposed two-dimensional model of the oxidative coupling of methane (OCM) to C2 hydrocarbons (e.g., C2H4 and C2H6) in a fixed bed reactor operated under isothermal and non-isothermal conditions is described which can provide more accurate predictions of experimental data than the simplified one-dimensional model. The model includes a set of partial differential equations of the continuity, mass transfer and energy balance equations. The performance of the OCM using different catalysts was assessed in terms of CH4 conversion, C2 selectivity and C2 yield with respect to key operating parameters, such as feed temperature (973-1173 K), CH4/O2 ratio (3.4–7.5) and gas hour space velocity (GHSV) (18000-30000 h-1). The simulation results indicated that the Na-W-Mn/SiO2 catalyst exhibits the best performance among all of the catalysts. The C2 yield were 20.16% and 20.00% for non-isothermal and isothermal modes respectively which the OCM reactor is operated at a CH4/O2 ratio of 3.4, a feed temperature of 1073 K and a GHSV of 9720 h-1. An increase in the operating temperature increases the CH4 conversion but decreases the C2 selectivity. However, the effects of the CH4/O2 ratio and the GHSV exhibit an opposite trend to that of the operating temperature.A proposed two-dimensional model of the oxidative coupling of methane (OCM) to C2 hydrocarbons (e.g., C2H4 and C2H6) in a fixed bed reactor operated under isothermal and non-isothermal conditions is described which can provide more accurate predictions of experimental data than the simplified one-dimensional model. The model includes a set of partial differential equations of the continuity, mass transfer and energy balance equations. The performance of the OCM using different catalysts was assessed in terms of CH4 conversion, C2 selectivity and C2 yield with respect to key operating parameters, such as feed temperature (973 - 1173 K), CH4/O2 ratio (3.4 – 7.5) and gas hour space velocity (GHSV) (18000 - 30000 h-1). The simulation results indicated that the Na-W-Mn/SiO2 catalyst exhibits the best performance among all of the catalysts. The C2 yield were 20.16% and 20.00% for non-isothermal and isothermal modes respectively which the OCM reactor is operated at a CH4/O2 ratio of 3.4, a feed temperature of 1073 K and a GHSV of 9720 h-1. An increase in the operating temperature increases the CH4 conversion but decreases the C2 selectivity. However, the effects of the CH4/O2 ratio and the GHSV exhibit an opposite trend to that of the operating temperature

Oxidative Coupling of Methane over YSZ Support Catalysts for Application in C2 Hydrocarbon Production

This paper studies the development of Mn-Na2WO4 catalysts on YSZ support for oxidative coupling of methane reaction. It can be divided into two parts; (1) study in fixed bed reactor (FBR), and (2) study in solid oxide fuel cell reactor (SOFC). In part I, the experiments were performed using co-feeds of methane, oxygen and nitrogen inert gas at a ratio of 4:1:5 for different temperatures (973 - 1173 K). Mn-Na2WO4 catalyst on YSZ support was doped with sulfur, phosphorous, and cerium in order to improve its catalytic reactivity. The results indicated that sulfur and phosphorous showed the good improvement for Mn-Na2WO4 catalyst on YSZ support. At 1073 K, S-Mn-Na2WO4/YSZ provided C2 selectivity of 60.3% and methane conversion of 31.1%, while P-Mn- Na2WO4/YSZ offered C2 selectivity of 59.8% and methane conversion of 34.1%. P-Mn-Na2WO4/YSZ catalyst was selected as anode catalysts for further study in the SOFC reactor. The experiments were carried out using La0.8Sr0.2MnO3 (LSM) as the cathode catalyst, 8 mol% yttria-stabilized zirconia (YSZ) as the electrolyte. P-Mn-Na2WO4/YSZ exhibited the best performance, providing C2H4 selectivity of 89.0%, methane conversion of 10.5% and maximum power density of 7.2 W/m2 at 1123 K. In addition, the stability of the P-Mn-Na2WO4/YSZ catalyst was tested at 1123 K. Good stability of the reaction system could be observed at least for 29 hours

Review of Non-Thermal Plasma Technology for Hydrogenation of Vegetable Oils and Biodiesel

The hydrogenation of lipid derivative compounds has received much attention as it is one of the key chemical reactions of industrial processes to improve the physical and chemical properties of those compounds such as thermal resistance, cold flow properties, oxidative stability, etc. The principle of hydrogenation of vegetable oil for margarine production relies on the addition of hydrogen to the carbon double bond positions of fatty acid molecules to become a single bond, increasing the saturated fatty acids until the texture becomes semi-solid. The partial addition of hydrogen to biodiesel improves its oxidation resistance. At present, industrial-scale using catalytic hydrogenation of lipid derivative compounds operates under high temperature and high-pressure environments, leading to a high trans-fat content in the products and requiring catalyst separation from the product. Non-thermal plasma (NTP) technology as a green process can be deployed to substitute conventional hydrogenation, on a laboratory scale for the time being, because no catalyst is required and the process can occur at near ambient temperature and low or atmospheric pressure. Moreover, trans-fat formation is several times lower than that of catalytic hydrogenation. The present review article provides more insight into the various types of NTP technology for lipid derivative compounds hydrogenation, including discussions on different experimental setup configurations, parameters affecting plasma hydrogenation, properties of synthesized products, as well as the advantages and drawbacks of environmentally-friendly plasma hydrogenation compared to conventional catalytic hydrogenation

Performance of Membrane-Assisted Solid Oxide Fuel Cell System Fuelled by Bioethanol

The membrane separation units for bioethanol purification including pervaporation and vapor permeation are integrated with the bioethanol-fuelled solid oxide fuel cell (SOFC) system. The preliminary calculations indicate that Hydrophilic type is a suitable membrane for vapor permeation to be installed after a hydrophobic pervaporation. Based on energy self-sufficient condition and data of available pervaporation membranes, the simulation results show that the use of vapor permeation unit after the pervaporation can significantly improve the overall electrical efficiency from 10.96% for the system with pervaporation alone to 26.56%. Regarding the effect of ethanol recovery, the ethanol recovery at 75% can offer the optimal overall efficiency from the proposed purification system compared to the ethanol recovery at 31.16% for the case with the single pervaporation

Reviews on Solid Oxide Fuel Cell Technology

oai:www.engj.org:article/25Solid Oxide Fuel Cell (SOFC) is one type of high temperature fuel cell that appears to be one of the most promising technology to provide the efficient and clean energy production for wide range of applications (from small units to large scale power plants). This paper reviews the current status and related researches on SOFC technologies. In details, the research trend for the development of SOFC components(i.e. anode, electrolyte, cathode, and interconnect) are presented. Later, the current important designs of SOFC (i.e. Seal-less Tubular Design, Segmented Cell in Series Design, Monolithic Design and Flat Plate Design) are exampled. In addition, the possible operations of SOFC (i.e. external reforming, indirect internal reforming, and direct internal reforming) are discussed. Lastly, the research studies on applications of SOFCs with co-generation (i.e. SOFC with Combined Heat and Power (SOFC-CHP), SOFC with Gas Turbine (SOFC-GT)) and SOFC with chemical production) are given