Zhaoping Zhong

Biomass fast pyrolysis in a fluidized bed reactor under N2, CO2, CO, CH4 and H2 atmospheres.

Biomass fast pyrolysis is one of the most promising technologies for biomass utilization. In order to increase its economic potential, pyrolysis gas is usually recycled to serve as carrier gas. In this study, biomass fast pyrolysis was carried out in a fluidized bed reactor using various main pyrolysis gas components, namely N(2), CO(2), CO, CH(4) and H(2), as carrier gases. The atmosphere effects on product yields and oil fraction compositions were investigated. Results show that CO atmosphere gave the lowest liquid yield (49.6%) compared to highest 58.7% obtained with CH(4). CO and H(2) atmospheres converted more oxygen into CO(2) and H(2)O, respectively. GC/MS analysis of the liquid products shows that CO and CO(2) atmospheres produced less methoxy-containing compounds and more monofunctional phenols. The higher heating value of the obtained bio-oil under N(2) atmosphere is only 17.8 MJ/kg, while that under CO and H(2) atmospheres increased to 23.7 and 24.4 MJ/kg, respectively.

Microwave-assisted catalytic fast pyrolysis of biomass for bio-oil production using chemical vapor deposition modified HZSM-5 catalyst.

Chemical vapor deposition with tetra-ethyl-orthosilicate as the modifier was applied to deposit the external acid sites of HZSM-5, and the modified HZSM-5 samples were used for the microwave-assisted catalytic fast pyrolysis (MACFP) of biomass for bio-oil production. The experimental results showed that the external acid sites of HZSM-5 decreased significantly when SiO2 deposited amount increased from 0% to 5.9%. For product distribution, the coke yield decreased, the oil fraction yield decreased at first and then increased, and the yields of water and gas first increased and then decreased over the range of SiO2 deposited amount studied. For chemical compositions in oil fraction, the relative contents of aliphatic hydrocarbons, aromatic hydrocarbons and oxygen-containing aromatic compounds first increased to maximum values and then decreased, while the relative content of oxygen-containing aliphatic compounds first decreased and then increased with increasing SiO2 deposited amount.

Catalytic fast co-pyrolysis of biomass and food waste to produce aromatics: Analytical Py–GC/MS study

In this study, catalytic fast co-pyrolysis (co-CFP) of corn stalk and food waste (FW) was carried out to produce aromatics using quantitative pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS), and ZSM-5 zeolite in the hydrogen form was employed as the catalyst. Co-CFP temperature and a parameter called hydrogen to carbon effective ratio (H/C(eff) ratio) were examined for their effects on the relative content of aromatics. Experimental results showed that co-CFP temperature of 600 °C was optimal for the formation of aromatics and other organic pyrolysis products. Besides, H/C(eff) ratio had an important influence on product distribution. The yield of total organic pyrolysis products and relative content of aromatics increased non-linearly with increasing H/C(eff) ratio. There was an apparent synergistic effect between corn stalk and FW during co-CFP process, which promoted the production of aromatics significantly. Co-CFP of biomass and FW was an effective method to produce aromatics and other petrochemicals.

Gasification characteristics of MSW and an ANN prediction model

Gasification characteristics make up the important parts of municipal solid waste (MSW) gasification and melting technology. These characteristics are closely related to the composition of MSW, which alters with climates and seasons. It is important to find a practical way to predict gasification characteristics. In this paper, five typical kinds of organic components (wood, paper, kitchen garbage, plastic, and textile) and three representative types of simulated MSW are gasified in a fluidized-bed at 400-800 degrees C with the equivalence ratio (ER) in the range of 0.2-0.6. The lower heating value (LHV) of gas, gasification products, and gas yield are reported. The results indicate that gasification characteristics are different from sample to sample. Based on the experimental data, an artificial neural networks (ANN) model is developed to predict gasification characteristics. The training and validating relative errors are within +/-15% and +/-20%, respectively, and predicting relative errors of an industrial sample are below +/-25%. This indicates that it is acceptable to predict gasification characteristics via ANN model.

Experimental study on MSW gasification and melting technology.

In order to develop municipal solid waste (MSW) gasification and melting technology, two preliminary experiments and a principle integrated experiment were fulfilled respectively. The gasification characteristics of MSW were studied at 500-750 degrees C when equivalence ratio (ER) was 0.2-0.5 using a fluidized-bed gasifier. When temperature was 550-700 degrees C and ER was 0.2-0.4, low heat value (LHV) of syngas reaches 4000-12000 kJ/Nm3. The melting characteristics of fly ash were investigated at 1100-1460 degrees C using a fixed-bed furnace. It was proved that over 99.9% of dioxins could be decomposed and most heavy-metals could be solidified when temperature was 1100-1300 degrees C. The principle integrated experiment was carried out in a fluidized-bed gasification and swirl-melting system. MSW was gasified efficiently at 550-650 degrees C, swirl-melting furnace maintains at 1200-1300 degrees C stably and over 95% of fly ash could be caught by the swirl-melting furnace. The results provided much practical experience and basic data to develop MSW gasification and melting technology.

Tests on co-firing of municipal solid waste and coal in a circulating fluidized bed

Energy recovery from municipal solid waste (MSW) is a feasible method through various processes, such as combustion, pyrolysis and gasification. Tests on the co-firing of MSW and coal were conducted in a 0.2 MWth circulating fluidized bed, and the emissions of NO, N2O, HCl and SO2 were studied. A three layer feed forward neural network was constructed and trained by the BP method with experimental data. The impacts of mixing ratio and bed temperature on the gaseous emissions were considered. The model predicted gaseous pollutions emissions were consistent with experimental data.

Application of mineral bed materials during fast pyrolysis of rice husk to improve water-soluble organics production

Fast pyrolysis of rice husk was performed in a spout-fluid bed to produce water-soluble organics. The effects of mineral bed materials (red brick, calcite, limestone, and dolomite) on yield and quality of organics were evaluated with the help of principal component analysis (PCA). Compared to quartz sand, red brick, limestone, and dolomite increased the yield of the water-soluble organics by 6-55% and the heating value by 16-19%. The relative content of acetic acid was reduced by 23-43% with calcite, limestone and dolomite when compared with quartz sand. The results from PCA showed all minerals enhanced the ring-opening reactions of cellulose into furans and carbonyl compounds rather than into monomeric sugars. Moreover, calcite, limestone, and dolomite displayed the ability to catalyze the degradation of heavy compounds and the demethoxylation reaction of guaiacols into phenols. Minerals, especially limestone and dolomite, were beneficial to the production of water-soluble organics.

Characteristic and mercury adsorption of activated carbon produced by CO2 of chicken waste

Preparation of activated carbon from chicken waste is a promising way to produce a useful adsorbent for Hg removal. A three-stage activation process (drying at 200 degrees C, pyrolysis in N2 atmosphere, followed by CO2 activation) was used for the production of activated samples. The effects of carbonization temperature (400-600 degrees C), activation temperature (700-900 degrees C), and activation time (1-2.5 h) on the physicochemical properties (weight-loss and BET surface) of the prepared carbon were investigated. Adsorptive removal of mercury from real flue gas onto activated carbon has been studied. The activated carbon from chicken waste has the same mercury capacity as commercial activated carbon (Darco LH) (Hg(v): 38.7% vs. 53.5%, Hg(0): 50.5% vs. 68.8%), although its surface area is around 10 times smaller, 89.5 m2/g vs. 862 m2/g. The low cost activated carbon can be produced from chicken waste, and the procedure is suitable.

Two-step fast microwave-assisted pyrolysis of biomass for bio-oil production using microwave absorbent and HZSM-5 catalyst.

A novel technology of two-step fast microwave-assisted pyrolysis (fMAP) of corn stover for bio-oil production was investigated in the presence of microwave absorbent (SiC) and HZSM-5 catalyst. Effects of fMAP temperature and catalyst-to-biomass ratio on bio-oil yield and chemical components were examined. The results showed that this technology, employing microwave, microwave absorbent and HZSM-5 catalyst, was effective and promising for biomass fast pyrolysis. The fMAP temperature of 500°C was considered the optimum condition for maximum yield and best quality of bio-oil. Besides, the bio-oil yield decreased linearly and the chemical components in bio-oil were improved sequentially with the increase of catalyst-to-biomass ratio from 1:100 to 1:20. The elemental compositions of bio-char were also determined. Additionally, compared to one-step fMAP process, two-step fMAP could promote the bio-oil quality with a smaller catalyst-to-biomass ratio.

Characterization of Pyrolytic Lignin Extracted from Bio-oil

Bio-oil is a new liquid fuel produced by fast pyrolysis, which is a promising technology to convert biomass into liquid. Pyrolytic lignin extracted from bio-oil, a fine powder, contributes to the instability of bio-oil. The paper presents the structural features of three kinds of pyrolytic lignin extracted from bio-oil with different methods (WIF, HMM, and LMM). The pyrolytic lignin samples are characterized by Fourier transform infrared spectrometer (FTIR) and X-ray photoelectron spectroscopy (XPS). FTIR data indicate that the three pyrolytic lignin samples have similar functional groups, while the absorption intensity is different, and show characteristic vibrations of typical lignocellulosic material groups OH (3340–3380 cm−1), CH (2912–2929 cm−1) and CO (1652–1725 cm−1). Comparison in the region (3340–3380 cm−1) indicates that WIF has more OH stretch groups than HMM and LMM. The carbon spectra are fitted to four peaks: C1, CC or CH, BE = 283.5 eV; C2, COR or COH, BE = 284.5–285.8 eV; C3, CO or HOCOR, BE = 286.10–287.10 eV; C4, OCO, BE = 287.5–287.7 eV. The absence of C1, CC or CH indicates the dominant polymerization structure of aromatic carbon in pyrolytic lignin samples. For HMM and WIF, C2a and C2b can not be separated, so there is no free hydroxyl group in the samples. The oxygen peaks are also fitted to four peaks: O1, OH, BE = 530.3 eV; O2, RCO, BE = 531.45–531.72 eV; O3, OCO, BE = 532.73–533.74 eV; O4, H2O, BE = 535 eV. The absence of O1 and O4 indicates that little hydroxyl groups and adsorbed water are present in the samples.