Browsing by Subject "char"
Now showing 1 - 2 of 2
Results Per Page
Sort Options
Item Elucidating the solid, liquid and gaseous products from batch pyrolysis of cotton-gin trash.(2009-05-15) Aquino, Froilan LudanaCotton-gin trash (CGT) was pyrolyzed at different temperatures and reaction times using an externally-heated batch reactor. The average yields of output products (solid/char, liquid/bio-oil, and gaseous) were determined. The heating value (HV) of CGT was measured to be around 15-16 MJ kg- 1 (6500-7000 Btu lb-1). In the first set of tests, CGT was pyrolyzed at 600, 700, and 800?C and at 30, 45, and 60 min reaction period. The maximum char yield of 40% by weight (wt.%) was determined at 600?C and 30 min settings, however, the HV of char was low and almost similar to the HV of CGT. A maximum gas yield of 40 wt.% was measured at 800?C and 60 min and the highest liquid yield of 30 wt.% was determined at 800?C and 30 min. In the modified pyrolysis test, the effects of temperature (500, 600, 700, and 800?C) on the product yield and other properties were investigated. The experiment was performed using the same reactor purged with nitrogen at a rate of 1000 cm3 min-1. Gas yield increased as temperature was increased while the effect was opposite on char yield. The maximum char yield of 38 wt.% was determined at 500?C and 30 min. The char had the largest fraction in the energy output (70-83%) followed by gas (10-20%) and bio-oil (7- 9%). Maximum gas yield of 35 wt.% was determined at 800?C. The average yield of CO, H2 and total hydrocarbons (THC) generally increased with increased temperature but CO2 production decreased. Methane, ethane, and propane dominated the THC. The bio-oil yield at 600?C was the highest at about 30 wt.% among the temperature settings. The HV of bio-oil was low (2-5 MJ kg-1) due to minimal non-HC compounds and high moisture content (MC). A simple energy balance of the process was performed. The process was considered energy intensive due to the high amount of energy input (6100 kJ) while generating a maximum energy output of only 10%. After disregarding the energy used for preparation and pyrolysis, the energy losses ranged from 30-46% while the energy of the output represent between 55-70% of the input energy from CGT.Item Multi-Proxy Approach on Black Carbon Characterization and Combustion Products Source Discrimination in Environmental Media(2011-02-22) Kuo, Li-JungEnvironmental applications of pyrogenic carbon, aka black carbon (BC), have been hampered due to the poor characterization and quantification of environmental BC. This dissertation was dedicated to the better characterization of environmental char/charcoal BC (char-BC), the most heterogeneous and the less identifiable group in the BC continuum. The analytical approach developed for char-BC was further incorporated with other BC methods in environmental samples for a comprehensive assessment of combustion-derived carbon inputs in different environmental systems. The present study firstly evaluated the feasibility of using levoglucosan, a marker derived from cellulose/hemocellulose combustion, to characterize and quantify char-BC in the environment. Levoglucosan was found exclusively in BC materials derived from biomass combustion albeit in highly variable yields across different char-BC. A further examination of synthetic chars showed that temperature is the most influential factor affecting levoglucosan yield in char. Notably, levoglucosan was only detectable in low temperature char samples (150-350 degrees C), regardless of plant species. These results demonstrated that levoglucosan could serve as a good qualitative indicator for the presence of char produced under low temperature conditions in soil, sediments, and aerosols. Results of lignin analysis on the synthetic chars further reveal that combustion can greatly decrease the yield of the eight major lignin phenols with no lignin phenols detected in any synthetic char produced at greater than or equal to 400 degrees C. The values of all lignin parameters show significant shifts with increasing combustion severity (temperature and/or duration), indicating that thermal alteration is an important abiotic lignin degradation process. Hence the input of char-BC in the environments represents a terrestrial organic matter source with highly altered lignin signatures. Finally, a multi-proxy approach, including elemental (soot-BC) and molecular (levoglucosan, polycyclic aromatic hydrocarbons (PAHs), and lignin oxidation products) proxies, was adopted to investigate the centennial-scale temporal distribution of combustion products in four sediment cores from Puget Sound basins, WA. The observed temporal trends of soot-BC and combustion PAHs fluxes reflect the evolution of energy consumption and the positive effects of environmental regulations. The distinct temporal patterns of soot and PAHs among cores demonstrate that urbanization is a crucial factor controlling the inputs of combustion byproducts to the environment. On the other hand, the trends of levoglucosan may be more relevant to the climate oscillation and thus show a regional distribution pattern. Our results demonstrate that environmental loading of combustion byproducts is a complex function of urbanization and land use, fuel usage, combustion technology, environmental policies, and climate changes.