摘要:

Evaluation is presented of the thermogravimetric behavior of four types of rice husk (Lemont, ROK 14, CP 4, and Pa Potho) at three heating rates (10, 20, and 50 degrees C min) in air, oxygen, and nitrogen atmospheres. The thermal degradation rate in active and passive zones, the initial degradation temperature, and the residual weight at 700 degrees C were determined. These thermal degradation indices are dependent on the heating rate, atmosphere employed, inorganic substances in rice husk, and chemical composition of rice husk. The initial degradation temperature decreased, while both the thermal degradation rate and the residual weight at 700 degrees C increased when the heating rate was increased. The higher the cellulosic content of the rice husk, the higher the thermal degradation rate and the initial degradation tempera ture. Also, higher ash content in the rice husk resulted in a higher residual weight at 700 degrees C. The thermal degradation rate in the active zone was higher in the presence of oxygen than in the presence of air and nitrogen. More residual weight was recorded in the nitrogen atmosphere compared to the oxidative atmospheres of the air and oxygen atmospheres. The residual weights of the rice husk samples at 700 degrees C in air and oxygen atmospheres were lower than their initial ash contents, with percentages of ash lost ranging from about 2.95 to 13.10 % in the case of air and 4.20 to 17.05 % in the case of oxygen.

ISSN:0090-8312    

DOI:10.1080/00908319950014254

出版商:Informa UK Ltd    

年代:1999

数据来源: Taylor

摘要:

This article summarizes the results obtained from the physical, chemical, and mineralogical characterization of 14 fly ash samples. Major features that influence the utilization of each fly ash for zeolite synthesis are evidenced, and several fly ash types were selected as potential high-quality starting material for zeolite synthesis and ceramic applications. The main parameters influencing this selection were relatively small grain size; high Al and Si contents; high glass content; low CaO, S, and Fe contents; and relatively low heavy metal concentration. The Compostilla and Dou He fly ashes have high potential applications because of the low content of major impurities (such as Ca, Fe, and S) and the low content of soluble hazardous elements. The Espiel, Escucha, Los Barrios, As Pontes, Soto de Ribera, Meirama, Narcea, and Teruel fly ashes have important application potential, but this potential is slightly limited by the intermediate content of nonreactive impurities, such as Fe and Ca. The La Robla fly ash is of moderate interest, since the relatively high Ca and Fe oxide contents may reduce its potential applications. Finally, the Puertollano fly ash also has limited application because of the very high concentration of some heavy metals such as As, Cd, Ge, Hg, Pb, and Zn. From a mineralogical point of view, the Compostilla, Espiel, and Soto de Ribera fly ashes show the highest aluminum-silicate glass content and, consequently, the highest industrial application potential.

ISSN:0090-8312    

DOI:10.1080/00908319950014263

出版商:Informa UK Ltd    

年代:1999

数据来源: Taylor

摘要:

Rice husk is produced in large quantities as a by-product of rice milling in rice-producing countries and has posed disposal problems in these countries. Disposal of or energy recovery from rice husk can be accomplished by thermochemical conversion processes (pyrolysis, combustion, and gasification). However, it appears that the kinetics of rice husk, which can contribute to the accurate modeling and design of thermochemical conversion processes, have not been studied extensively. In this paper the technique of thermogravimetric analysis (TGA) was used to study the thermochemical behavior of four varieties of rice husk (Lemont LG, ROK 14, CP 4, and Pa Potho). The thermal degradation of rice husk was studied in an air atmosphere (21 % oxygen and 79 % nitrogen) from ambient temperature to 700 degrees C at the heating rate of 20 degrees C min-1. The thermograms showed two distinct reaction zones. The kinetic parameters (activation energy, preexponential factor, and order of reaction) were determined for the two reaction zones by applying thermoanalytical techniques to the reaction kinetics. Higher thermal degradation rates were observed in the first reaction zone due to rapid release of volatiles as compared to those in the second reaction zone. In the first reaction zone the activation energies ranged from 37.0 to 54.7 kJ mol-1. Relatively lower activation energies (18.0 - 21.0 kJ mol-1) were obtained in the second reaction zone. The preexponential factors were in the range of 4.3 x 104 to 6.4 x 10 6 min- 1 in the first reaction zone and 4.5 x 102 to 1.5 x 103 min- 1 in the second reaction zone. The orders of reaction were in the range of 1.2 - 1.6 and 0.4 - 0.5 for the first and second reaction zones, respectively. The predicted thermal degradations were in good agreement with the experimental data in both the first and second reaction zones.

ISSN:0090-8312    

DOI:10.1080/00908319950014272

出版商:Informa UK Ltd    

年代:1999

数据来源: Taylor

摘要:

This article gives an overview of energy and water potential of the Southeastern Anatolia Project (GAP) in Turkey. This integrated socioeconomic development project is one of the largest of its kind in the world. The GAP region is rich in water and soil resources. The Euphrates and Tigris Rivers represent over 28 % of the nation's water supply by rivers, and the economically irrigatable areas in the region make up 20 % of those for the entire country. On the other hand, the GAP region is the richest region of the country in terms of its hydroelectric potential as well as its oil and asphalt reserves. The GAP region has a 22 % share of the country's total hydroelectric potential, with plans for 22 dams and 19 hydropower plants. Once completed, 27 billion kWh of electricity will be generated. In addition to this hydropower and oil potential, the GAP region is also the richest region of Turkey as far as solar energy production is concerned. In meeting the energy requirements of the developing regions worldwide and in Turkey, solar energy is being taken into account as an important renewable source of energy.

ISSN:0090-8312    

DOI:10.1080/00908319950014281

出版商:Informa UK Ltd    

年代:1999

数据来源: Taylor

摘要:

The Kingdom of Saudi Arabia is blessed with abundant solar energy, which is renewable, clean, and freely available. This paper describes the status of the major research, development, and demonstration (RD & D) activities and achievements at the Energy Research Institute, King Abdulaziz City for Science and Technology, in the field of solar energy. RD & D activities in the Kingdom have confirmed that solar energy has a multitude of practical uses. These include lighting, cooling, cooking, water heating, crop fruit drying, water desalination, operating irrigation pumps, and meteorological stations, and providing road and tunnel lighting. Furthermore, these solar energy RD & D activities and achievements played a significant role in transfer ring technology and manpower development in the Kingdom.

ISSN:0090-8312    

DOI:10.1080/00908319950014290

出版商:Informa UK Ltd    

年代:1999

数据来源: Taylor

摘要:

Evaluation of the results of a carbonization process is usually carried out by means of indicators such as mass yield, energy yield, or balanced mass yield. However, these indicators have some limits or drawbacks. A new indicator, the reference mass yield, is defined, based on the results of a well-controlled laboratory experimentation. This reference mass yield combines the mass yield and the fixed carbon content of the charcoal. It is a constant independent of the fixed carbon content, hence of the carbonization temperature. Some carbonization results from the literature are evaluated by means of the reference mass yield.

ISSN:0090-8312    

DOI:10.1080/00908319950014308

出版商:Informa UK Ltd    

年代:1999

数据来源: Taylor

摘要:

Source rock maturity and potential of Paleozoic and Mesozoic formations in the Eregli, Zonguldak, Bartin, Ulus, and Eflani subregions of the western Black Sea region (WBSR), have been investigated by rock-eval pyrolysis, reflected-light microscopy, and palynofacies analyses. The % Ro values of dispersed organic matter of the Paleozoic formations primarily range from 0.72 to 1.8 %, but values as high as 2.6 % occur locally in the Silurian Findikli Formation in the Eregli subregion. The % Ro values of Namurian-Westphalian coal seams in the K20 H well drilled in the Zonguldak subregion range from 0.87 to 1.52 %, with increasing depth consistent with sedimentary depth of burial. Most Cretaceous age samples have reflectance values ranging from 0.44 to 1.6% Ro that indicates they are marginally mature to mature with respect to the oil window. Rock-eval pyrolysis demonstrates that the Paleozoic formations have limited oil-generation potential (HI values < 200 mg HC/gCo rg), but good gas potential (TOC values up to 3 %). Cretaceous formations have better petroleum source rock characteristics, but they too are primarily gas prone. Variations in the source rock maturity probably reflect variable burial histories in different localities of the WBSR.

ISSN:0090-8312    

DOI:10.1080/00908319950014317

出版商:Informa UK Ltd    

年代:1999

数据来源: Taylor

摘要:

The H-donor ability of different rank coals was examined by using a copper(II)chlo ride-acetonitrile system as the dehydrogenator. A bituminous coal and two lignites were irradiated in the UV in the presence of copper(II)chloride in acetonitrile. The coal was dehydrogenated while the Cu(II) was reduced to Cu(I). Considerable amounts of aliphatic or alicyclic hydrogen were removed from the coals. In the process, while the oxygen contents of coals do not increase, more condensed aromatic products occur. It was concluded that lignites are better reducing agents than bituminous coals. A photooxidation mechanism is proposed on the basis of the model compound reaction. Photooxidation of alcohols (ethanol, 2-propanol, benzyl alcohol, 4-hydroxybenzyl alcohol, and diphenyl carbinol), a hydroaromatic com pound (tetrahydronaphthalene), and an aromatic ether (dibenzyl ether) was per formed under similar reaction conditions.

ISSN:0090-8312    

DOI:10.1080/00908319950014326

出版商:Informa UK Ltd    

年代:1999

数据来源: Taylor