Lawrence L. Tavlarides

Supercritical biodiesel production and power cogeneration: technical and economic feasibilities.

An integrated supercritical fluid technology with power cogeneration to produce biodiesel fuels, with no need for the costly separations involved with the conventional technology, is proposed, documented for technical and economic feasibility, and preliminarily designed. The core of the integrated system consists of the transesterification of various triglyceride sources (e.g., vegetable oils and animal fats) with supercritical methanol/ethanol. Part of the reaction products can be combusted by a diesel power generator integrated in the system which, in turn, provides the power needed to pressurize the system and the heat of the exhaust gases necessary in the transesterification step. The latter energy demand can also be satisfied by a fired heater, especially for higher plant capacities. Different versions of this system can be implemented based on the main target of the technology: biodiesel production or diesel engine applications, including power generation. The process options considered for biodiesel fuel production estimate break-even processing costs of biodiesel as low as

Determination of diffusion coefficients by supercritical fluid chromatography: Effects of mobile phase mean velocity and column orientation.

0.26/gal (

Sol-gel synthesized adsorbents for metal separation

0.07/L) with a diesel power generator and

Design of a Small Pilot Plant for the Study of Supercritical Processes for the Production of Biodiesel from Waste Chicken Fat

0.35/gal (

Tritium Specific Adsorption Simulation Utilizing the OSPREY Model

0.09/L) with a fired heater for a plant capacity of 15,000 gal/day (56,775 L/day). Both are significantly lower than the current processing costs of approximately

Investigations on supercritical transesterification of chicken fat for biodiesel production from low-cost lipid feedstocks

0.51/gal (

Integrated Technology for Supercritical Biodiesel Production and Power Cogeneration

0.13/L) of biodiesel produced by conventional catalytic methods. A retail cost of biodiesel produced by the proposed method is likely to be competitive with the prices of diesel fuels.

Biodiesel Fuels through a Continuous Flow Process of Chicken Fat Supercritical Transesterification

The supercritical fluid (SCF) chromatographic technique based on the Taylor dispersion theory has been widely applied in determination of diffusion coefficients of various organic compounds in SCFs. This study was aimed to understand impacts of mobile phase mean velocity (MPMV) and column orientation on diffusion coefficient measurements. The benzene/SCCO(2) system was investigated. Experiments were carried out at 40 and 60 degrees C and 9-15 MPa over a wide range of CO(2) densities at varying MPMV and repeated in two column orientations, vertical and horizontal. It was found that both MPMV and column orientation significantly affected measurements of diffusion coefficients in SCFs. When the column was installed vertically, apparent diffusion coefficients obtained at relatively low CO(2) density (<580 kg/m(3)) increased with increasing MPMV over the entire velocity ranges. This results in a conclusion that diffusion coefficients cannot be accurately determined under these conditions using a vertically installed column. Under all other conditions, as MPMV increased, apparent diffusion coefficients initially increased, then remained constant, and finally increased again. The initial increase of apparent diffusion coefficients was associated with significant decline of curve-fitting errors, which indicates that the buoyancy effects are non-negligible and will cause larger errors. Accordingly, a new generalized D(12)-U diagram comprised of three regions is proposed. Column orientation affected diffusion coefficient measurements mainly by enhancing or weakening the buoyancy effects. When the column was installed vertically, the buoyancy effects were enhanced, leading to lower apparent diffusion coefficients, especially when CO(2) density was relatively low. In addition, it was found that when CO(2) density was below approximately 580 kg/m(3), diffusion coefficients obtained when the column was horizontally installed were higher than those obtained when the same column was vertically installed. When CO(2) density was above that value, opposite outcomes resulted. Finally, the horizontal orientation of a diffusion column is recommended for diffusion coefficient measurements by the SCF chromatographic technique, especially when densities of SCFs are relatively low.

Adsorption of chromium(VI) from aqueous solutions using an imidazole functionalized adsorbent

Abstract A series of organo-ceramic adsorbents have been synthesized by a sol-gel processing technique for metal ion extraction. These adsorbents generally have significantly high metal uptake capacities, good physical-chemical stabilities, and well-designed pore geometries compared to other pre-existing metal-chelating ceramic-based adsorbents. This work describes the synthesis and evaluation of pyrazole and calix[4]arene crown adsorbents for selective separation of platinum, palladium, and gold and cesium ions, respectively, from solutions. These materials exhibit mesoporous properties with high surface areas and pore volumes. The sol-gel synthesis starting with precursor silanes and titania results in gel particles of desired pore characteristics and high capacity and stability. Characterization studies, such as adsorption isotherms, breakthrough curves for fixed bed operation, and material stability, show promising results for applications to metal sepation.

Production of biodiesel from microalgae oil (Chlorella protothecoides) by non-catalytic transesterification in supercritical methanol and ethanol: Process optimization

A process to produce biodiesel from chicken fat and other oils using supercritical methanol at 200 bars and 400oC with residence times 6-9 minutes was designed using CHEMCAD. Major process units for the process (pumps, heat exchangers, reactor, and distillation columns) were sized and the heating and cooling requirements for several process variations were evaluated. Methanol to oil ratios or 6/1, 9/1 and 9/1 with recycle were considered. The results were then used to estimate the cost of a small pilot plant to produce 2 gal/day of biodiesel fuel.