摘要:

The use of agricultural residues for power production has generated increasing interest in the conversion of rice husks to higher quality fuels by thermochemical conversion processes such as pyrolysis, combustion, and gasification. However, the reliable design and operation of thermochemical conversion systems requires consid erable knowledge of rice husk thermal degradation characteristics and kinetics. The thrust of this paper therefore was to study the reaction kinetics of four varieties of rice husk at a heating rate of 20 degrees C min-1 in an inert atmosphere of pure nitrogen (99.5% nitrogen, 0.5% oxygen) using thermogravimetric analysis and derivative thermogravimetric techniques. The thermal degradation characteristics and the kinetic parameters (activation energy, preexponential factor, and order of reaction) were determined for the two prominent reaction zones from the thermogravimetric curves. Thermal degradation rates in the first reaction zone were relatively higher than those in the second reaction zone. The initial degradation temperatures were 220, 232, 223, and 240 degrees C for the rice husk varieties Lemont LG, ROK 14, CP 4, and Pa Potho, respectively. Residual weights recorded at 700 degrees C were in the range of 33.9 - 38.7%. Higher activation energies (29.0 - 35.4 kJ mol-1) and preexponential factors (4.7 x 103 to 6.4 x 104 min-1) were obtained for all rice husk varieties in the first reaction zone as compared to those of the second reaction zone (15.1 - 17.7 kJ mol-1 and 1.0 x 102 to 5.1 x 102 min-1 for the activation energy and preexponential factor, respectively). The order of reactions was in the range of 0.90 - 1.08 for the first reaction zone and 0.30 - 0.36 for the second reaction zone.

ISSN:0090-8312    

DOI:10.1080/00908319950014335

出版商:Informa UK Ltd    

年代:1999

数据来源: Taylor

摘要:

We investigated a remediation process for diesel-contaminated soil, in which water was used to remove the diesel from the soil and peat was used to absorb the diesel layer formed on the surface of the water. The percolation of water through the soil was uniform. The time required for water to percolate the soil and for the layers (soil, water, and diesel) to separate depended on the soil depth. Both the depth of soil and mixing affected the thickness of the diesel layer and thus diesel revovery from the contaminated soil. Higher diesel recovery was achieved with smaller soil depth and mixing. The initial moisture content and the lower heating value of the peat were 7.1% and 17.65 MJ/kg, respectively. The final moisture content and lower heating value of the diesel-contaminated peat obtained from the experiment with mixing were 8.65 - 10.80% and 32.57 - 35.81 MJ/kg, respectively. The energy content of the diesel-contaminated peat is much higher than that of coal, and the moisture content is within the range recommended for biomass gasification.

ISSN:0090-8312    

DOI:10.1080/00908319950014344

出版商:Informa UK Ltd    

年代:1999

数据来源: Taylor

摘要:

Oil seed plants are important biomass energy sources. The rapeseed plant, which yields a high amount of vegetable oil, has a major position among other oil seed plants. In this study the straw stalk of the rapeseed plant (type 00 Brassica napus L.) has been investigated as a candidate for a biomass energy source.

ISSN:0090-8312    

DOI:10.1080/00908319950014353

出版商:Informa UK Ltd    

年代:1999

数据来源: Taylor

摘要:

In the present study the effects of sodium carbonate as a leachant in desulfurization of Mengen lignite were investigated. A kinetic study was also carried out, and the shrinking core model was proposed to describe the kinetic data of pyritic sulfur removal. The highest sulfur removal percentages were observed for total and sulfate sulfur as 36.2% and 97.1%, respectively, with the use of a coal alkali solution volume ratio of 1/70 at 120 degrees C. Desulfurization of Mengen lignite with 100 mL of 0.2 M aqueous sodium carbonate solution at 140 degrees C for 3 hours caused 96% removal of pyritic sulfur. It was also observed that the rate of leaching increased significantly with temperature and alkali solution concentration.

ISSN:0090-8312    

DOI:10.1080/00908319950014362

出版商:Informa UK Ltd    

年代:1999

数据来源: Taylor

摘要:

The use of vegetable oils as fuel alternatives has an exceptional importance in the field of research. In this study, evaluation possibilities of cottonseed oil have been investigated as an alternative candidate for diesel fuel and fuel oil. The fuel property tests were performed according to standard analysis methods for oil and fuel. An overall evaluation of the results indicates that cottonseed oil can be proposed as a possible green substitute for fuel.

ISSN:0090-8312    

DOI:10.1080/00908319950014371

出版商:Informa UK Ltd    

年代:1999

数据来源: Taylor

摘要:

Sulfur removal from a high-sulfur Turkish lignite (Gediz) using aqueous sodium hydroxide solutions having dissolved oxygen was investigated under mild oxidative conditions. Effects of the parameters such as sodium hydroxide lignite weight ratio, temperature, and partial pressure of oxygen were investigated within the ranges of 0.05 - 0.8, 423 - 498 K, and 1 - 2 MPa, respectively. Optimum values of these parameters were determined regarding sulfur removal and coal recovery. Influences of dry oxidation of the lignite sample as a pretreatment at 573 K and subsequent washing of some treated lignite samples with 1 N HCl were investigated.

ISSN:0090-8312    

DOI:10.1080/00908319950014380

出版商:Informa UK Ltd    

年代:1999

数据来源: Taylor

摘要:

Previous work in our laboratories has demonstrated that addition of lignin to coal during liquefaction significantly increases the depolymerization of coal and enhances the quality of the liquid products. It is believed that thermolysis of the lignin results in the formation of phenoxy and other reactive radicals at temperatures too low for significant thermolysis of the coal matrix; such radicals are effective and active intermediates that depolymerize coal by cleaving methylene bridges. It has been reported that alkali is also effective for extraction of liquids from coal. The work presented here combines these two reactive agents by utilizing the black liquor waste stream from the Kraft pulping process for coal depolymerization. That waste stream contains large amounts of lignin and sodium hydroxide, as well as other components. To permit comparative evaluations of the extent of coal depolymerization by coprocessing coal and black liquor, reference runs were performed with tetralin alone, sodium hydroxide in tetralin, and lignin in tetralin. Results indicated that the sodium hydroxide-tetralin system resulted in almost 67% conversion at 375 degrees C, 1 hour. The black liquor system exhibited a lower conversion of 60%, indicating some inhibition of the depolymerization reactions by components in the black liquor.

ISSN:0090-8312    

DOI:10.1080/00908319950014399

出版商:Informa UK Ltd    

年代:1999

数据来源: Taylor

摘要:

Energy utilization patterns in the residential sector of Yerevan, Armenia, are exam ined based on 1997 survey data. Residential utilization patterns of electricity and energy are summarized, including the variation of consumption patterns between households of different income levels. Engel functions are estimated using regression techniques.

ISSN:0090-8312    

DOI:10.1080/00908319950014407

出版商:Informa UK Ltd    

年代:1999

数据来源: Taylor

ISSN:0090-8312    

DOI:10.1080/00908319950014416

出版商:Informa UK Ltd    

年代:1999

数据来源: Taylor