Experimental Investigation of Biogas Reforming in Gliding Arc Plasma Reactors

Biogas is an important renewable energy source. Its utilization is restricted to vicinity of farm areas, unless pipeline networks or compression facilities are established. Alternatively, biogas may be upgraded into synthetic gas via reforming reaction. In this work, plasma assisted reforming of biogas was investigated. A laboratory gliding arc plasma setup was developed. Effects of CH4/CO2 ratio (1, 2.33, 9), feed flow rate (16.67–83.33 cm3/s), power input (100–600 W), number of reactor, and air addition (0–60% v/v) on process performances in terms of yield, selectivity, conversion, and energy consumption were investigated. High power inputs and long reaction time from low flow rates, or use of two cascade reactors were found to promote dry reforming of biogas. High H2 and CO yields can be obtained at low energy consumption. Presence of air enabled partial oxidation reforming that produced higher CH4 conversion, compared to purely dry CO2 reforming process

Design and Performance Analysis of a Biodiesel Engine Driven Refrigeration System for Vaccine Storage

A compact, stand-alone, refrigeration module powered by a small biodiesel engine for vaccine storage in rural use was proposed. The engine was of single cylinder, four-stroke, directinjection with displacement of 0.296 cm3 and compression ratio of 20:1. The refrigeration system was modified from an automotive vapor compression system. The system performance was analytically investigated. From the simulation, it was found to have acceptable operation over a range of speeds and loads. Performance of the system in terms of fuel consumption and torque tended to decrease with an increase in engine speed. The modular system was able to operate at cooling loads above 4.6 kW, with proper speed ratio between the engine and the compressor. Overall, primary energy ratio of the refrigeration was found to be maximum at 0.54

Development of a laboratory scale air plasma torch and its application to electronic waste treatment

Expansion in electrical and electronic equipment trade has led to significant increase in electronic waste which should be dealt with special priority due to its potential negative impact to the public health and the environment. Thermal plasma technology offers a very promising alternative of hazardous waste treatment for the near future. In this study, a laboratory scale apparatus for generating high temperature plasma flame was presented. Design of a 20 kW plasma torch system was based on a non transferred direct current arc discharge with air as a medium gas. In this investigation, measurements of temperature distribution were performed. It was shown that high temperature flames can be generated, comparable to those reported in the literature. The gas temperature was found to increase with an increase in power input. The flame temperature was found to further increase from 1210 K to 1480 K when a small amount of added fuel gas. Assessment of electronic waste treatment using the air plasma system in a batch operation was also carried out. It was shown that the system was able to convert the electronic waste into combustible gas and inert solid residues. High mass loss rate of bulk electronic waste was demonstrated

Prediction of small spark ignited engine performance using producer gas as fuel

Producer gas from biomass gasification is expected to contribute to greater energy mix in the future. Therefore, effect of producer gas on engine performance is of great interest. Evaluation of engine performances can be hard and costly. Ideally, they may be predicted mathematically. This work was to apply mathematical models in evaluating performance of a small producer gas engine. The engine was a spark ignition, single cylinder unit with a CR of 14:1. Simulation was carried out on full load and varying engine speeds. From simulated results, it was found that the simple mathematical model can predict the performance of the gas engine and gave good agreement with experimental results. The differences were within ±7%

Performance evaluation of premixed burner fueled with biomass derived producer gas

Energy consumption of liquefied petroleum gas (LPG) in ceramic firing process accounts for about 15–40% of production cost. Biomass derived producer gas may be used to replace LPG. In this work, a premixed burner originally designed for LPG was modified for producer gas. Its thermal performance in terms of axial and radial flame temperature distribution, thermal efficiency and emissions was investigated. The experiment was conducted at various gas production rates with equivalence ratios between 0.8 and 1.2. Flame temperatures of over 1200 °C can be achieved, with maximum value of 1260 °C. It was also shown that the burner can be operated at 30.5–39.4 kWth with thermal efficiency in the range of 84 – 91%. The maximum efficiency of this burner was obtained at producer gas flow rate of 24.3 Nm3/h and equivalence ratio of 0.84

Biomass gasification in a fixed bed downdraft ractor with oxygen enriched air: A modified equilibrium modeling study

Biomass conversion by gasification process is increasingly becoming attractive, especially for ceramic making industry, to transform biomass materials into combustible fuel gas called producer gas. This producer gas can then be used to fully or partially substitute liquefied petroleum gas in ceramic firing process. However, air gasification is known to generate low calorific value of gaseous fuel (3-6 MJ/Nm 3 ) which may not be able to generate sufficiently high temperature (> 1200 o C) flame required by ceramic firing process. Use of oxygen enriched air is therefore of great interest if medium to high calorific value producer gas is required. In this work, a modified equilibrium model of global gasification reactions is developed to predict the resultant distribution of combustible gas species in the producer gas and to study the effect of operating parameters (oxygen content in air, and equivalence ratio) in a gasification process of agro-residues in a fixed bed downdraft gasifier at a fixed temperature. The modified equilibrium model of global gasification reactions developed in this work is based on thermodynamically stoichiometric approach due to its simplicity and reduced computational time. Model predictions of reaction kinetic constants for gasification reactions and gas concentration are validated by comparing with available experimental data. Simulation of influence of oxygen content in air (21-50%) and equivalence ratio (0.15-0.35) on composition of combustible gas and its heating value is carried out. The preliminary model simulation is found to give good qualitative prediction of experimental results. For maximum calorific value of producer gas generated, oxygen content in air should be 50%, and the equivalence ratio should be 0.15, respectively. For better accuracy of this modified equilibrium model, unconverted char and tar should be further considered

Numerical Computation of Fluid Flow and Aerosol Transport in a Long Electrical Mobility Spectrometer

Size distribution of submicron airborne particles can be effectively determined using electrical mobility technique. In this study, a numerical computation model for prediction of fluid flow and aerosol transport in a long column, electrical mobility spectrometer (EMS) has been developed. The internal 3D structure of an EMS [Intra and Tippayawong (2009), Korean J. Chem. Eng., 26(1), 269] was employed to simulate the complex flow patterns and aerosol particle trajectories in the EMS, including the swirling flow developed near the sheath air inlet slit. The incompressible Navier-Stokes equations were numerically calculated for the gas flow and particle trajectories, with a commercial computational fluid dynamics software package, FLUENT 6.3. The calculated results were found to agree well with previously published results in the literature. Prediction of fluid flow and aerosol transport was particularly useful in the EMS design and development

Sustainable Energy from Biogas Reforming in a Microwave Discharge Reactor

AbstractBiogas is one of the most important renewable energy sources in modern societies. Generated from livestock manure and industrial wastewater, it can provide considerable savings in energy costs and reducing environmental impacts. Thailand is reported to have the potential to produce over one billion m3 of biogas a year. The biogas is generally utilized for heating, mechanical shaft works, and electricity generation. If pipeline networks or purification and compression facilities are not available, use of biogas is normally limited to only within and around farm areas. Alternatively, biogas may be converted via reforming reactions into synthetic gas. Because of presence of sulphur compounds in biogas, a catalytic reformer may face serious poisoning problem. In this work, non-catalytic, plasma assisted reforming of biogas was carried out at atmospheric pressure and room temperature in an 800W, laboratory microwave discharge reactor. Effects of CH4/CO2 ratio (1, 2.33, 9), feed flow rate (8.33 – 50 cm3/s), and oxygen addition in terms of CH4/O2 ratio (1, 1.5, 2) on reactor performance (yield, selectivity, conversion, H2/CO and energy consumption) was investigated. It was found that biogas was successfully reformed into synthetic gas by a microwave plasma reactor under room temperature and non-catalytic conditions. For dry reforming of biogas, high H2 and CO yields were obtained at low energy consumption. Presence of oxygen enabled partial oxidation reforming that produced higher CH4 conversion, compared to purely dry reforming process. By varying CH4/CO2 as well as CH4/O2 ratios, synthetic gas with a wide range of H2/CO ratios can be generated. From the findings, it was suggested that the microwave plasma reactor may be practically used to reform biogas to produce more valuable intermediates or products such as synthetic gas