Islam Ahmed

Chemical Energy Recovery from Polystyrene using Pyrolysis and Gasification

Ctemperature. Gasification of PS is affected by reactor temperature more than that under pyrolysis conditions. Syngas, hydrogen and energy yield increased exponentially with temperature in the case of gasification. However, syngas and energy yield increased linearly with temperature having rather a mild slope in the case of pyrolysis. Pyrolysis resulted in higher syngas quality at all temperatures. The detailed results obtained from pyrolysis and gasification obtained at the same reactor temperature are provided.

Syngas and Energy Yield from Residual Branches of Oil Palm Tree Using Steam Gasification

Different kinds of biomass and agriculture wastes are good source of renewable energy, especially in agriculture rich countries. These wastes can be converted to energy via either thermo-chemical process or bio-chemical process. The oil palm waste from agro-industry is a good source of renewable energy in agriculture rich countries, such as, Indonesia, Malaysia, and Thailand. This paper provides clean chemical energy generation via steam gasification from residual branches of oil palm fruit tree that are by-product of oil palm mill plants. Thermo-chemical energy transformation of residual waste from the oil palm fruit tree to chemical energy is performed using advanced high temperature steam gasification. A batch type gasifier has been used to investigate the gasification of palm trunk wastes at different temperatures for a fixed steam flow rate of 3.10 g/min. The results showed that gasification temperature only slightly affect the syngas yield. However, the composition of the syngas yield was much affected by the gasification temperature. This influenced the heating value and energy ratio; both increased with increase in gasification reactor temperature. The reaction time and steam to solid fuel ratio indicated that the reaction rate became progressively slowly at temperature below 700C. This suggests that steam gasification should not be carried out at temperature below 700C with oil palm tree residual wastes due to poor efficiency and increased char under such conditions.

Evolutionary Behavior of Gas Yield from Cardboard Pyrolysis

Evolutionary behavior on the yield of various gaseous components during pyrolysis of cardboard has been investigated using a batch reactor. Specifically the behavior of syngas flow rate and chemical properties of the syngas composition have been examined at various pyrolysis temperatures at different residence times of the cardboard in the reactor. The syngas properties determined include evolutionary behavior of concentrations of hydrogen, CO, CO 2 and hydrocarbons in the syngas as well as temporal behavior of volumetric flow rate. The temporal behavior of syngas heating value, output power, H 2/CO ratio, pure fuel percentage in syngas and apparent thermal efficiency have also been examined. The results showed that the reactor temperature has distinct effect on the evolutionary behavior of syngas properties during pyrolysis, specially the peak position of hydrogen yield and H 2/CO molar ratio. The time integral of syngas properties have also been investigated. The reactor temperature is found to be effective in controlling the overall syngas yield and properties of the syngas components during solid fuel pyrolysis.

On the Efficient Use of Rubber in Gasification Systems

*The characteristics of syngas evolution during pyrolysis and gasification of waste rubber have been investigated. A semi-batch reactor was used for the thermal decomposition of the material under various conditions of pyrolysis and high temperature steam gasification. The results are reported at two different reactor temperatures of 800 and 900 o C and at constant steam gasifying agent flow rate of 7.0 g/min and a fixed sample mass. The characteristics of syngas were evaluated in terms of syngas flow rate, hydrogen flow rate, syngas yield, hydrogen yield and energy yield. Gasification resulted in 500% increase in hydrogen yield as compared to pyrolysis at 800 o C. However, at 900 o C the increase in hydrogen was more than 700% as compared to pyrolysis. For pyrolysis conditions, increase in reactor temperature from 800 to 900 o C resulted in 64% increase in hydrogen yield while for gasification conditions a 124% increase in hydrogen yield was obtained. Results of syngas yield, hydrogen yield and energy yield from the rubber sample are evaluated with that obtained from woody biomass samples, namely hard wood and wood chips. Rubber gasification yielded more energy at the 900 o C as compared to biomass feedstock samples. However, less syngas and less hydrogen were obtained from rubber than the biomass samples at both the temperatures reported here.

Evolution of Syngas from Co-gasification of Polyethylene and Woodchips

Gasification of polyethylene (PE) and woodchips (WC) mixtures have been investigated in a semibatch reactor, using high temperature steam as the gasifying agent. The reactor temperature was maintained at 900 o C. The ratio of PE to WC was varied from 0% to 100% in 20% intervals. Characteristics of syngas were evaluated based on the yield of syngas, hydrogen, energy, total hydrocarbons and apparent thermal efficiency of the process. Results show that properties of syngas evolved during gasification of PE-WC blends cannot be determined from the weighted average syngas properties obtained from separate gasification of WC and PE. Superior results in terms of syngas yield, hydrogen yield, total hydrocarbons yield, energy yield and apparent thermal efficiency from PE-WC blends were obtained as compared to expected weighed average yields from the individual components. The results obtained support synergistic interaction between PE and WC during high temperature steam gasification of these mixtures. These results also reveal the importance of mixing two or more compounds on the performance of stream gasification of wastes. I. Introduction Greater use of renewable energy sources is of pinnacle importance especially with the limited reserves of fossil fuels. It is expected that future energy use will have increased utilization of different alternative sources of energy available to us, including biomass, municipal solid wastes, industrial wastes, agricultural wastes and other low grade fuels. These energy sources and wastes provide unique challenges for energy utilization since the energy yield and gas composition from gasification or pyrolysis of these materials is strongly impacted by the feed mixture composition. Development of sustainable renewable energy technologies for their use in current and new power plants is of greater importance now than ever before due to several reasons. Some of these reasons include energy security and availability, independency from foreign oils and reduction of greenhouse gas emissions to provide cleaner environment for better health and plant, and animal life. These reasons dictate the development of alternative and sustainable energy technologies. Gasification provides part of the solution towards dependable renewable energy source. Gasification is a robust solution to solve the growing problem of landfills, since energy can be fully extracted and the waste is destructed with minimum residue and with the properly developed process the remaining residue is non-leachable. Gasification systems may run on single or multiple sources of feedstock. However, in many cases the gasification systems often encounter the problem of unsteady source of biomass feed throughout the year so that the biomass composition cannot be taken as fixed. During off-season for a given biomass, another feedstock has to be mixed with the feedstock in order to maintain a steady supply of feedstock to the gasifier for seeking the desired output power from the gasification power plant. On the other hand, a gasification system might be designed to run on solid wastes, which consists of a mixture of different carbonaceous materials. However, the composition of the waste can change both temporally and spatially so that one must examine in detail the role of various input, design and operational parameters on the gasifier performance. Much attention has been given to evaluate the behavior of various kinds of single component materials under gasification or pyrolysis conditions. 1-5 Examining the characteristics and kinetics of single component samples provides basic information on the behavior of different samples for use as feedstock in gasification systems. This then helps in the better design of gasifiers for improved performance and controlled syngas composition of defined and higher heating value. However, the data obtained from single component experiments may result in some misleading information about the actual syngas properties and the process kinetics. The fate of multi-components as feed stock to the gasifier might be much different than the expected fate of single components. The misleading information might arise from the assumption that the syngas characteristics resulting from gasifying a mixture of

Pyrolysis and Steam Gasification of Paper and Evaluation of Paper Char Kinetics

Main characteristics of gaseous yield from steam gasification have been investigated experimentally. Results of steam gasification have been compared to that of pyrolysis. The temperature range investigated were 600 to 1000°C in steps of 100°C. Results have also been obtained under pyrolysis conditions at same temperatures. For steam gasification runs, steam flow rate was kept constant at 8.0 gr./Min.. Investigated characteristics were evolution of syngas flow rate with time, hydrogen flow rate, chemical composition of syngas, energy yield and apparent thermal efficiency. Residuals from both processes were quantified and compared as well. Material destruction, hydrogen yield and energy yield is better with gasification as compared to pyrolysis. This advantage of the gasification process is attributed mainly to char gasification process. Char gasification is found to be more sensitive to the reactor temperature than pyrolysis. Pyrolysis can start at low temperatures of 400 °C; however char gasification starts at 700 °C. A partial overlap between gasification and pyrolysis exists and is presented here. This partial overlap increases with increase in temperature. As an example, at reactor temperature 800 °C this overlap represents around 27% of the char gasification process and almost 95% at reactor temperature 1000°C.Copyright

Gasification Kinetics of Food Waste Char

*† Gasification is proven to be more beneficial than pyrolysis based on energy yield and waste destruction, but longer time is needed to finish the gasification process. Longer time of gasification is attributed to slow reactions between the residual char and gasifying agent. Consequently, the char gasification kinetics was investigated. Inorganic constituents of food char were found to have a catalytic effect. Char reactivity increased with increased degree of conversion. In the conversion range from 0.1 to 0.9 the increase in reactivity was accompanied by an increase in pre-exponential factor, which suggested an increase in gasifying agent adsorption rate to char surface. However, in the conversion range from 0.93 to 0.98 the increase in reactivity was accompanied by a decrease in activation energy. A compensation effect was observed in this range of conversion of 0.93 to 0.98.

Comparison of Pyrolysis and Steam Gasification of Paper

Main characteristics of gaseous yield from steam gasification of paper have been investigated experimentally. Results of steam gasification have been compared to that of pyrolysis. The temperature range investigated was 600 to 1000 o C in steps of 100 o C. Results have also been obtained under pyrolysis conditions at same temperatures. For steam gasification experiments, steam flow rate was kept constant at 8.0 g/min. Characteristic evolutionary behavior of syngas flow rate, hydrogen flow rate, chemical composition of syngas, energy yield and apparent thermal efficiency have been examined. Residuals from both the pyrolysis and gasification process have been compared and quantified. Material destruction, hydrogen yield and energy yield is superior with gasification as compared to pyrolysis. This advantage of the gasification process is attributed mainly to char gasification process. Char gasification is found to be more sensitive to reactor temperature than pyrolysis. Pyrolysis can start at low temperatures of 400 o C; however char gasification starts at about 700 o C. A partial overlap between gasification and pyrolysis exists and is presented here. This partial overlap increases with increase in temperature. As an example, at reactor temperature 800 o C this overlap represents around 27% of the char gasification process and almost 95% at reactor temperature 1000 o C.

High Temperature Gasification of Cardboard and Paper with CO2

0C substantial enhancement of the kinetics process occurred. The global behavior of syngas chemical composition examined at three different temperatures revealed a peak in concentration of H2 to exhibit after few minutes into the gasification that changed with gasification temperature. At 800 o C gasification temperature peak in H2 was displayed at 3 minutes into gasification while it decreased to only 2 minutes, approximately, at gasification temperatures of 900 o C and 1000 o C. The effect of reactor temperature on CO mole fraction has also been examined. Increase in the gasification temperature enhances the mole fraction of CO yields. This is attributed to the increase in forward reaction rate of the Boudouard reaction (C+CO2 Ÿ 2CO). The results show important role of CO2 gas for the gasification of wastes and low grade fuels to clean syngas.

Evolutionary Behavior of Syngas During Gasification

Evolutionary behavior of syngas characteristics evolved during the gasification of cardboard has been examined using a batch reactor with steam as a gasifying agent. Evolutionary behavior of syngas chemical composition, mole fractions of hydrogen, CO and CH 4, as well as H2/CO ratio, LHV (kJ/m 3 ), hydrogen flow rate, and percentage of combustible fuel in the syngas evolved has been examined at different steam to flow rates with fixed mass of waste cardboard. The effect of steam to carbon ratio as affect by the steam flow rate on overall syngas properties has therefore been examined. A new parameter called coefficient of energy gain (CEG) has been introduced that provides information on the energy gained from the process. This new parameter elaborates the importance of optimizing the sample residence time in the reactor.