To better understand biomass pyrolysis, the different roles of the three components (hemicellulose, cellulose, and lignin) in pyrolysis are investigated in depth using a thermogravimetric analyzer (TGA). The pyrolysis characteristics of the three components are first analyzed, and the process of biomass pyrolysis is divided into four ranges according to the temperatures specified by individual components. Second, synthesized biomass samples containing two or three of the biomass components are developed on the basis of a simplex-lattice approach. The pyrolysis of the synthesized samples indicates negligible interaction among the three components and a linear relationship occurring between the weight loss and proportion of hemicellulose (or cellulose) and residues at the specified temperature ranges. Finally, two sets of multiple linear-regression equations are established for predicting the component proportions in a biomass and the weight loss of a biomass during pyrolysis in TGA, respectively. The results of the calculations for the synthesized samples are consistent with the experimental measurements. Furthermore, to validate the computation approach, TGA experimental analysis of the three components of palm oil wastes, a local representative biomass sample, is conducted.
TMGL (tetramethylguanidinium lactate) is believed to be a potential medium for SO2 removal. However, direct use of TMGL in SO2 absorption exhibits unsatisfactory absorption rate and desorption performance, mainly because of its hyperviscosity. In this work, mesoporous molecular sieve MCM-41 (mobil composition of matter no. 41) was employed as support material to prepare a novel absorbent (MCM-41-TMGL). The uptake of SO2 depends on TMGL, and the absorption rate depends on the porous feature of MCM-41-TMGL. Results show that MCM-41-TMGL dramatically improved the absorption kinetics and desorption efficiency, largely attributed to enhanced gas–liquid interface. Moreover, the absorbed SO2 in MCM-41-TMGL can be easily stripped out by heating at 90 °C under vacuum, allowing MCM-41-TMGL-10% to maintain 95% of the initial absorption capacity after 10 cycles of regeneration. In addition, the absorption performance of MCM-41-TMGL was investigated under different conditions, including absorption temperature, SO2 concentration, and vapor concentration of simulated flue gas.
The running database of a power plant includes a great deal of professional data.It is difficult to discover the correlation between some parameters from those data,which appear inde-pendent.The framework of a PISE(Professional Intelligent Search Engine)is designed and intro-duced,which is developed using data mining and knowledge discovery technologies with professional arithmetic.PISE can mine out the correlation between given parameters from running database of power plant and administer these professional rules discovered.An application example based on the actual running database of a power plant is given.This project is supported by Special Case of Central Finance in2001ofContemporary Long-distance Education Project(Document 215of Technology Department ,Ministry of Edu-cation).
Chemical looping combustion (CLC) with syngas, a synthesized gas mixture of CO, H2, CO2, H2O(g), N2, and H2S, was investigated using thermodynamic simulation, with focus on carbon deposition and sulfur evolution in CLC. Five metal oxides, such as NiO, CuO, Fe2O3, Mn3O4, and CoO, were selected as oxygen carriers for CLC application. Different influencing factors on the formation of carbon deposits were investigated, including pressure, fuel reactor (FR) temperature, oxygen excess number Φ (denoting the availability of lattice oxygen in the oxygen carrier to the fuel), and fuel gas composition. Higher temperature and larger oxygen excess number Φ inhibited the formation of carbon deposits while the pressurized condition caused the opposite. The increase of H2O(g) and CO2 fraction in syngas reduced carbon deposition while, in contrast, a larger H2S occurrence in syngas led to more carbon deposits to be formed. A sensitivity analysis to the different factors revealed that carbon deposition was mainly determined by the FR temperature and the oxygen carriers provided while other factors played a minor role. In addition, the predominant C-bearing species and their distributions at different temperatures were thermodynamically investigated. At low FR temperature and oxygen-deficient condition (i.e., oxygen excess number Φ < 1), the predominant carbon species as solid deposits were mainly elemental carbon or carbonates for NiO, CuO, Fe2O3, and CoO while MnC2 and MnCO3 were the main species for Mn3O4. In terms of the evolution of sulfur in CLC with syngas containing a basic composition of CO, N2, H2, and H2S, the low pressure, high temperature, and adequate lattice oxygen would make more sulfur species form in the gas phase. After that, CO2 and H2O(g) were introduced into the syngas, and they were found to possibly serve as additional oxidizers to convert H2S into SO2. The oxidation function of CO2 was slightly stronger than that of steam. Again, the evolution and distribution of various sulfur species was studied. For four metal oxides (NiO, Fe2O3, Mn3O4, and CoO), the most possible solid sulfur compounds were Ni3S2, Fe0.84S, MnSO4, and Co0.89S, respectively. But for CuO, at Φ < 1, Cu2S was the main solid sulfur compound while at Φ > 1 CuSO4 and Cu2SO4 dominated.
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