Haiyu Meng

Synergistic effect on thermal behavior during co-pyrolysis of lignocellulosic biomass model components blend with bituminous coal.

Co-thermochemical conversion of lignocellulosic biomass and coal has been investigated as an effective way to reduce the carbon footprint. Successful evaluating on thermal behavior of the co-pyrolysis is prerequisite for predicting performance and optimizing efficiency of this process. In this paper, pyrolysis and kinetics characteristics of three kinds of lignocellulosic biomass model components (cellulose, hemicellulose, and lignin) blended with a kind of Chinese bituminous coal were explored by thermogravimetric analyzer and Kissinger-Akahira-Sunose method. The results indicated that the addition of model compounds had different synergistic effects on thermal behavior of the bituminous coal. The cellulose showed positive synergistic effects on the thermal decomposition of the coal bituminous coal with lower char yield than calculated value. For hemicellulose and lignin, whether positive or negative synergistic was related to the mixed ratio and temperature range. The distribution of the average activation energy values for the mixtures showed nonadditivity performance.

Study on product distributions and char morphology during rapid co-pyrolysis of platanus wood and lignite in a drop tube fixed-bed reactor.

The rapid co-pyrolytic behavior of platanus wood and Pingzhuang lignite was explored in a drop tube fixed-bed reactor under nitrogen atmosphere. Synergistic effects were evaluated using the deviations between experimental and predicted values of product yields and gas components. Surface morphology of residual chars were also investigated applying the scanning electron microscopy technique (SEM). This study found that the experimental values of gas volume yields were greater than the predicted, and the maximum gas volume yield exhibited with 50% biomass blending ratio at 1000°C. Positive or negative synergistic effects happened in gas components at different blending ratios and temperatures. The SEM results indicated that the differences of char surface morphology were evident. The fractal dimensions of residual chars increased with increasing biomass blending ratio, which may improve their gasification or combustion reactivity. The change in product yields and gas components was attributed to the secondary reactions and tar cracking.

Physico-chemical properties and gasification reactivity of co-pyrolysis char from different rank of coal blended with lignocellulosic biomass: Effects of the cellulose

In this paper, the influence of cellulose on the physicochemical properties and the gasification reactivity of co-pyrolysis char was investigated. A specific surface area analyzer and an X-ray diffraction system were used to characterize the pore structure and the micro-crystalline structure of char. Fractal theory and deconvolution method were applied to quantitatively investigate the influence of cellulose on the structure of co-pyrolysis char. The results indicate that the improvements in the pore structure due to the presence of cellulose are more pronounced in the case of anthracite char with respect to bituminous char. Cellulose promotes the ordering of micro-scale structure and the uniformity of both anthracite and bituminous char, while the negative synergetic effect was observed during gasification of co-pyrolysis char. The exponential relationships between fractal dimension and specific surface area were determined, along with the relations between the gasification reactivity index and the microcrystalline structure parameter.

Investigation on Thermal and Kinetic Characteristics During Co-Pyrolysis of Coal and Lignocellulosic Agricultural Residue

Co-utilization of coal and lignocellulosic biomass has the potential to reduce greenhouse gases emission from energy production. As a fundamental step of typically thermochemical co-utilization (e.g., co-combustion, co-gasification), co-pyrolysis of coal and lignocellulosic biomass has remarkable effect on the conversation of the further step. Thermal behavior and kinetic analysis are prerequisite for predicting co-pyrolysis performance and modeling co-gasification and co-combustion processes. In this paper, co-pyrolysis behavior of a Chinese bituminous coal blended with lignocellulosic agricultural residue (wheat straw collected from north of China) and model compound (cellulose) were explored via thermogravimetric analyzer. Bituminous coal and lignocellulosic agricultural residue were heated from ambient temperature to 900 °C under different heating rates (10, 20, 40 °C·min−1) with various mass mixing ratios (coal/lignocellulosic agricultural residue ratios of 100, 75/25, 50/50, 25/75 and 0). Activation energy were calculate via iso-conversional method (eg. Kissinger-Akahira-Sunose, Flynn-Wall-Ozawa and Starink methods). The results indicated that pyrolysis rate of coal was accelerated by wheat straw under all mixing conditions. Cellulose promoted the pyrolysis rate of coal under equal or lesser than 50% mass ratio. Some signs about positive or passive synergistic effect were found in char yield. Char yields were lower than that calculated from individual samples for bituminous coal and wheat straw. With the increasing of cellulose mass ratio, the positive synergies on char yields were reduced, resulting in passive synergistic effect especially under higher coal/cellulose mass ratio (25/75). Nonlinearity performance was observed from the distribution of activation energy.Copyright

Investigation on Gaseous Product Distributions During Co-Pyrolysis of Platanus Wood and Different Rank Coals From Northwestern China in a Drop Tube Furnace

Co-thermochemical conversion of municipal solid waste blends with coal has the advantage of diversifying energy resources and decreasing consumption of fossil fuels. As the initial and fundamental stage of co-thermochemical conversion, co-pyrolysis of municipal solid waste and coal has important influence on performance of the further co-combustion or co-gasification process. In this paper, gaseous product distributions during co-pyrolysis of platanus wood (wood waste from urban roadside trees platanus acerifolia) and two different rank coals (Shenmu bituminous and Pingzhuang lignite from northwestern China) were investigated through a semi-batch type drop tube furnace at different temperatures. The platanus wood/coal blends were fed into the furnace with five different mass ratios of 100/0, 70/30, 50/50, 30/70, and 0/100. The gaseous products (H2, CO, CO2, CH4 and light hydrocarbons) were continuously collected and then determined by gas chromatography. Experimental results indicated that the gaseous product distributions from pyrolysis of the platanus wood and coal blends were significantly affected by the temperature, the platanus wood/coal mass ratio and coal type. Compared the experimental results with the calculated values obtained from individual samples based on weighted average, some signs about positive or negative synergistic effect were observed on the formation of the major gas composition. The synergistic effect could probably be caused by the secondary reactions between volatiles and chars. In addition, the coal rank appeared to have different influence on the synergistic effect between platanus wood and coal during co-pyrolysis process.Copyright

Investigation on Thermal and Kinetic Characteristics During Pyrolysis and Co-Pyrolysis of Recovered Fuels Obtained From Municipal Solid Waste in China

Alternative fuels, such as municipal solid waste (MSW) tend to play an increasingly important role in Chinese energy supply. Gasifying fuels derived from MSW have the potential of covering a significant part of the future demand on gasification capacities. However, their pyrolysis behaviour was not clear due to that the reactions during co-pyrolysis of the MSW serval fractions have not yet been fully investigated. In this paper, thermal behavior of pork, polypropylene and their blends were investigated by thermogravimetry under pyrolysis conditions via the non-isothermal thermogravimetric analysis. The pyrolysis and co-pyrolysis kinetics characteristics of the waste samples was investigated at a temperature range of 50 to 1000 °C with the heating rate of rate of 10, 20, 40 °C·min−1 and for particle sizes less than 74 μm. The results indicated that pyrolysis rate of pork was hindered by polypropylene. Negative synergistic effects on mixture decomposition was observed. Weight loss of mixture were lower than that calculated from individual samples for pork and polypropylene. The apparent activation energy were obtained through Kissinger and Ozawa methods for the samples. The results indicated that more energy for blends to be decomposed during co-pyrolysis.© 2015 ASME