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Publications (6)23.75 Total impact

  • [show abstract] [hide abstract]
    ABSTRACT: Oxy-fuel or O2/CO2 combustion technology was used to investigate the combustion of Chlorella vulgaris by thermogravimetric analysis (TGA). Oxy-fuel combustion occurs in an O2/CO2 atmosphere instead of an O2/N2 atmosphere and offers an alternative method of C. vulgaris preparation for biofuels processing. Our results show that three stages were observed during C. vulgaris combustion and the main combustion process occurred at the second stage. Compared with a 20%O2/80%N2 atmosphere, the mass loss rate at the DTG peaks (Rp) and the average reaction rate (Rv) in a 20%O2/80%CO2 atmosphere was lower, while the ignition temperature (TI) was higher. As oxygen concentration increases in an O2/CO2 atmosphere, Rp, Rv and the apparent activation energy (E) increases, while TI, the final temperature detected as mass stabilization (Tf) and the residue mass (Mr) decreases; As the heating rate (β) increases, TI, Tf and Rp increase, while Mr decreases.
    Bioresource Technology 07/2013; · 4.75 Impact Factor
  • Longjun Li, Xiaoqian Ma, Qing Xu, Zhifeng Hu
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    ABSTRACT: The work was to investigate the influence of microwave power, metal oxides and metal salts onto the pyrolysis of algae (4.55wt.% moisture). It was found that the heating rate and the final temperature would increase as enhancing the microwave power. When microwave power increased from 750W to 2250W, the yield of solid residue decreased by 22.05%, and gas yield increased 39.45%. After adding 5% (mass basis) CuO and MgO, the yield of solid residue and bio-oil appeared the greatest decreasing ranges of 14.35% and 11.04%, respectively. Electrical energy consumption increased by 1.44% and reduced by 40.76% after CuO and MgO was added, separately. When algae was mixed with 5% (mass basis) MgCl2, ZnCl2 and NaH2PO3, respectively, the yield of solid residue increased by 3.98%, 1.13% and 2.31%, and the bio-oil yield increased by 6.3%, 16.92% and 0.71%, respectively. The effect of microwave absorption was ZnCl2>NaH2PO3>MgCl2.
    Bioresource Technology 05/2013; 142C:469-474. · 4.75 Impact Factor
  • Zhifeng Hu, Xiaoqian Ma, Longjun Li
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    ABSTRACT: The fast pyrolysis of Chlorella vulgaris was carried out in a quartz tube reactor under different pyrolysis temperature levels. The product fractional yields, gaseous products and the evaluation method based on heating value and energy consumption were analyzed in order to obtain the optimal condition to produce syngas. The results indicated that the higher the pyrolysis temperature level was, the higher the bio-fuel yield was. 900°C is the best temperature to obtain the maximum bio-fuel yield (91.09wt.%). And the highest emission of CO and H2 were achieved under the pyrolysis temperature of 800 and 900°C, respectively. According to the evaluation method based on heating value and energy consumption, there was a significant impact on the syngas production under different pyrolysis temperatures. Furthermore, the evaluation method based on energy consumption indicated that 800°C was the optimal pyrolysis temperature to produce syngas.
    Bioresource Technology 05/2013; 140C:220-226. · 4.75 Impact Factor
  • Chunxiang Chen, Xiaoqian Ma, Yao He
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    ABSTRACT: To find out an alternative of coal saving, a kind of microalgae, Chlorella vulgaris (C. vulgaris) which is widespread in fresh water was introduced into coal pyrolysis process. In this work, the pyrolysis experiments of C. vulgaris and coal blend (CCB) were carried out by TGA, and those of C. vulgaris and coal were also taken respectively as control groups. It was found that: the TG and DTG profiles of CCB were similar to C. vulgaris, but different from coal under various blending ratios; DTG profiles of CCB were different at several heating rates; interaction was observed between the solid phases of CCB; kinetic triplets were determined by the Kissinger-Akahira-Sunose (KAS), Flynn-Wall-Ozawa (FWO), and master-plots method, respectively. The results provide a reference for further study on co-pyrolysis of microalgae and coal to a certain extent.
    Bioresource Technology 04/2012; 117:264-73. · 4.75 Impact Factor
  • Zhifeng Hu, Xiaoqian Ma, Chunxiang Chen
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    ABSTRACT: The microwave-assisted pyrolysis of Chlorella vulgaris was carried out under different microwave power levels, catalysts and contents of activated carbon and solid residue. The products, pyrolysis temperature and temperature rising rate were analyzed in order to obtain the optimal conditions. The results indicated that the higher the microwave power level was, the higher the maximum temperature rising rate and pyrolysis temperature were. The maximum bio-oil yield (35.83 wt.%) and gas yield (52.37%) were achieved under the microwave power of 1500 W and 2250 W, respectively. And 2250 W was the optimal power to obtain bio-fuel product. High microwave power level and catalyst can enhance the production of gas. Catalysts can promote the pyrolysis of C. vulgaris, and activated carbon was the best among the tested catalysts followed by the solid residue. The optimal content of activated carbon is 5% with the maximum bio-fuel yield of 87.47%.
    Bioresource Technology 03/2012; 107:487-93. · 4.75 Impact Factor
  • Chunxiang Chen, Xiaoqian Ma, Kai Liu
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    ABSTRACT: Recently, studies of microalgae in China have increased a lot because of their obvious advantages over other biological fuels. In this paper, the combustion behavior of Chlorella vulgaris (a genus of unicellular green microalgae) was investigated in a thermogravimetric analyzer (TGA) from room temperature to 800°C in O2/N2 atmospheres. The effects of different oxygen concentrations (20, 50, 60, 80vol.%) and different heating rates (10, 20 and 40°Cmin−1) on the combustion processes of C. vulgaris had been studied. The results indicated that the combustion processes of C. vulgaris could be divided into three stages. The oxygen concentrations and heating rates had important effects on the main combustion processes of C. vulgaris. The iso-conversional method involving Flynn–Wall–Ozawa (FWO) and the Kissinger–Akahira–Sunose (KAS) methods were used for the kinetic analysis of the main combustion process. The results indicated that, when the oxygen concentration varied from 20 to 80vol.%, the value of activation energy increased respectively from 134.03 to 241.04kJmol−1 by using FWO method and from 134.53 to 242.33kJmol−1 by KAS method. Moreover, the optimal oxygen concentration for C. vulgaris combustion was 25–35vol.%.
    Applied Energy - APPL ENERG. 01/2011; 88(9):3189-3196.