Abstract

The purpose of this study was to evaluate the effects of temperature and equivalence ratios (ERs) on the distribution of products (primary gases carbon monoxide [CO], H2, CH4, CO2), gas phase contaminants (tar, NH3, HCN, H2S, HCl), char, carbon, and inorganics), and energy flows on an oxygen-blown bubbling fluidized bed gasifier system using loblolly pine. The goal and value of this study was to provide quantitative and qualitative performance analysis and data for process engineering and optimization of these fledgling biomass conversion systems. As temperature and ER increased, mass balance closures also increased from 94.73% to 96.72% for temperature and 89.82–96.93% for ER. In addition, the carbon closures ranged from 80.77% to 92.29% and from 79.09% to 87.13% as temperature and ER increased, respectively. Carbon conversion efficiency to gas product ranged from 72.26% to 84.32% as temperature increased and from 72.26% to 84.66% as ER increased. Carbon flow analysis showed that the char product streams retained 10.26–6.94% and 8.82–2.13% of the carbon fed to the gasifier as temperature and ER increased, respectively. The carbon content in the liquid condensate was minimal compared to the carbon in other product streams and accounted for less than 0.1% of the carbon input to the gasifier at all conditions. The cold and hot gas efficiencies increased from 56.12% to 67.45% and from 67.51% to 83.83% as temperature increased due to higher production of CO and hydrogen (H2). In contrast, cold and hot gas efficiencies decreased from 63.85% to 52.84% and from 78.06% to 73.00% as ER increased, respectively, due to enhanced oxidation of gas products resulting in a net decrease in heating value.

Abstract

The use of Permeable Reactive Barriers as a material for the removal of heavy metals from the leachates of the Sanitary Landfills has been verified for various materials, the Silica Sand from the coasts of the municipality of Alvarado Veracruz in Mexico have the characteristics of size and composition Required to be used for this purpose, samples of leachate were collected from the Sanitary Landfill of the City of Veracruz and the concentrations of Ni, Cr+6 and Zn were determined were respectively 0.0818, 0.186 and 0.224 mg/l, three columns were built of acrylic and were filled with 20, 30 and 40 cm of washed and dried Silica Sand, treated and stabilized leachate was passed through the porous medium at a flow of 1.7 ml/s, taking samples at 40.75, 115 , 165 and 235 seconds for each column and the efficiency for the removal of these heavy metals was measured and a significant reduction of these pollutants was found, ranging from 76 to 93%. for Nickel, from 44 to 81 % in the case of hexavalent Chromium and from 65 to 92% for Zinc for a maximum time of 235 seconds, which indicates that this material can be used in the remediation of leachate.