Lester O Pordesimo

Co-gasification of hardwood chips and crude glycerol in a pilot scale downdraft gasifier.

Seeking appropriate approaches to utilize the crude glycerol produced in biodiesel production is very important for the economic viability and environmental impacts of biodiesel industry. Gasification may be one of options for addressing this issue. Co-gasification of hardwood chips blending with crude glycerol in various loading levels was undertaken in the study involving a pilot scale fixed-bed downdraft gasifier. The results indicated that crude glycerol loading levels affected the gasifiers performance and the quality of syngas produced. When crude glycerol loading level increased, the CO, CH(4), and tar concentrations of the syngas also increased but particle concentration decreased. Though further testing is suggested, downdraft gasifiers could be run well with hardwood chips blending with liquid crude glycerol up to 20 (wt%). The syngas produced had relatively good quality for fueling internal combustion engines. This study provides a considerable way to utilize crude glycerol.

Mold appearance and modeling on selected corn stover components during moisture sorption.

Occurrence of mold was visually monitored for 26days on samples of major anatomical components of corn stover maintained at several storage temperatures (T) and water activities (a(w)). Glass desiccators with saturated salt solutions placed in temperature controlled chambers provided simulated storage conditions with temperatures ranging from 10 degrees C to 40 degrees C and water activities ranging from 0.11 to 0.98. Mold affected leaf, stalk skin, and stalk pith equally at water activity greater than 0.9. As expected, a combination of increased water activity greater than 0.9 and temperatures greater than 30 degrees C was conducive to mold growth. Based on material moisture content during the initial mold growth, it was postulated that among the corn stover components the stalk pith was the least resistant to mold growth followed by stalk skin and leaf for the studied range of temperature and water activity. Mold growth models fitted well with the observation. A linear mold-free days predictions using a three-parameter regression model (T, a(w), and T x a(w)) was superior (R(2)=0.99) to other models considered. The exponential spoilage model using two parameter T and a(w) also gave comparable performance (R(2)=0.95). Among the independent factors, T x a(w) product was the most significant (p=0.0069) followed by T (p=0.0114), and a(w) (p=0.3140) in explaining the experimental data. The developed models can be applied to predict the safe storage period of corn stover components exposed to various temperature and moisture environmental conditions.

High Temperature Water Gas Shift Reaction over Nickel Catalysts for Hydrogen Production: Effect of Supports, GHSV, Metal Loading, and Dopant Materials

The paper presents the recent advances of water-gas shift process using supported nickel catalysts. The effect of different supports, nickel loading, gas hourly space velocity, dopant materials, on the catalyst activity, H2 yield, and H2 selectivity are discussed. Ceria promoted nickel catalyst supported on powder alumina (Ni/CeO2-Al2O3) demonstrated the best performance. The performance of this catalyst was affected by the amount of nickel loading. The addition of small amounts of cobalt or chromium as a dopant material resulted in a considerable increase of the catalyst performance. The prepared catalysts were also compared with a commercial catalyst (Shift Max 120). It was observed that either of the doped or undoped Ni/CeO2-Al2O3 catalysts revealed a much higher performance in term of activity, H2 yield, and H2 selectivity, as compared to a commercial one.

Physical property effects on drying of Chile peppers.

Understanding effects of pepper fruit physical properties on pepper drying allows for improvement in postharvest handling and processing plus development of better cultivars. Drying tests with jalapeño peppers demonstrated that while dimensions of pepper fruits were decreasing with progressive harvests there was essentially no difference in the drying trends of peppers from the first harvest to the last. Slicing produced a similar drying trend for cultivars distinctly different in physical properties. Speed in drying peppers averaging 89.4% moisture to the 10–11% (w.b.) safe storage level was promoted by slicing as well as drying temperatures as high as 115oC.

Evaluation of micro-scale syngas production costs through modeling.

Feasibility of biomass gasification is very much dependent on the cost of the gasification facility and its operation. A cost analysis model was accordingly developed to analyze the unit cost of syngas production from micro-scale biomass gasification facilities. Costs considered included all capital and operating costs. The model was applied to evaluate a scenario for Mississippi in 2008. Results of the modeling indicated that operating cost was the major part of the syngas production cost, and the single-shift operating cost could be up to 83.64% of the total annual cost of syngas production at the 60 Nm3 h-1 capacity level. Labor cost was the largest part of the operating cost and the total annual cost. The labor cost could be up to 73.60% of the total of annual operating cost and 61.56% of the total annual cost of syngas production. The unit cost and energy cost of syngas production of the 60 Nm3 h-1 facility were

Hygroscopic Moisture Sorption Kinetics Modeling of Corn Stover and its Fractions

0.55 Nm-3 and

Ground Biomass Sieve Analysis Simulation by Image Processing and Experimental Verification of Particle Size Distribution

0.095 MJ-1, respectively, which were higher than the

Effects of Drying Procedure, Cultivar, and Harvest Number on Capsaicin Levels in Dried Jalapeno Peppers

0.357 Nm-3 and

Cost Analysis of Micro-Scale Biomass Gasification Facilities through Mathematical Modeling

0.009 MJ-1 natural gas average retail prices in the U.S. in the fourth quarter of 2008. When the production capacity increased, the total syngas production annual cost continually increased, but the syngas unit cost markedly decreased. Therefore, the effective way to reduce costs is to plan for a higher-capacity micro-scale facility. Sensitivity analysis showed that, from the lower bound to the upper bound of the production capacity range tested (60 to 1800 Nm3 h-1), there was a shift from labor cost to equipment cost as the factor of greatest influence on syngas unit cost. Such information provided by the model identifies considerations for planning and/or operating micro-scale gasification facilities. The model can be a tool for analyzing the economics of syngas production and, in that regard, it can generate useful information for the design of smaller gasification plants.

Potential of Dimensional Measurements of Individual Pellets as another Measure for Evaluating Pellet Quality

Corn stover, a major crop-based lignocellulosic biomass feedstock, is required to be at an optimum moisture content for efficient bioconversion processes. Environmental conditions surrounding corn stover, as in storage facilities, affect its moisture due to hygroscopic sorption or desorption. The measurement and modeling of sorption characteristics of corn stover and its leaf, husk, and stalk fractions are useful from utilization and storage standpoints, hence investigated in this article. A benchtop low-temperature humidity chamber provided the test environments of 20°C, 30°C, and 40°C at a constant 95% relative humidity. Measured sorption characteristics with three replications for each fraction were obtained from instantaneous sample masses and initial moisture contents. Observed sorption characteristics were fitted using exponential, Page, and Peleg models. Corn stover fractions displayed a rapid initial moisture uptake followed by a slower sorption rates and eventually becoming almost asymptotic after 25 h. Sorption characteristics of all corn stover fractions were significantly different (P 0.05) on these fractions. The initial 30 min of sorption was found to be critical due to peak rates of sorption from storage, handling, and processing standpoints. The Page and Peleg models had comparable performance fitting the sorption curves (R2 = 0.995), however the exponential model (R2 = 0.91) was not found suitable because of patterned residuals. The Arrhenius type relationship (P < 0.05; R2 = 0.80) explained the temperature variation of the fitted sorption model parameters. The Peleg model fitted constants, among the sorption models studied, had the best fit (R2 = 0.93) with the Arrhenius relationship. A developed method of mass proportion, involving individual corn stover fraction dry matter ratios, predicted the whole corn stover sorption characteristics from that of its individual fractions. Sorption characteristics models of individual corn stover fractions and predicted whole corn stover including a nomogram can be used for direct and quick estimation. Developed sorption characteristics find application in several fields of corn stover biomass processing, handling, and transport.