Shanhong Li

Co-hydrothermal carbonization of food waste-woody biomass blend towards biofuel pellets production

Co-hydrothermal carbonization of food waste-woody biomass blend was conducted to enhance the pelletization and hydrochar-fuel properties. The hydrochar was characterized by proximate, elemental analysis and HHVs, whilst energy consumption of pelletization, tensile strength, and combustion characteristics of hydrochar pellets were evaluated. Results showed that food waste (FW) blended with 0-50% mainly decreased H/C of hydrochar, while blend ratio from 75% to 100% mainly decreased O/C. When FW blended from 0% to 75%, the energy consumption for hydrochar palletization decreased about 12-17 J, whereas tensile strength of pellets increased about 2.4-5.5 MPa by formation of solid bridge when woody biomass (WS) ratio was increased. The hydrochar pellets from high ratio FW had decreased ignition temperature and maximum weight loss rate with wider temperature range, indicating the increased flammability and moderate combustion. These findings demonstrate that HTC of food waste-woody biomass blend was suitable for pelletization towards solid biofuel production.

Effects of cake collapse caused by deposition of fractal aggregates on pressure drop during ceramic filtration.

A cake collapse model was developed by taking the combined effects of fractal dimension, relaxation ratio, coordination number, and aggregate diameter into consideration. The cake porosity including intraaggregate and interaggregate porosities was modeled successively by three typical coordination numbers (n = 6, 8, and 12). Accordingly, an inversion method made it possible to deduce the coordination number using the measured cake porosities, and the reverse-calculated value with minimum error and the corresponding relaxation ratios were applied as the parameters for the model. As a result, the profiles of intraaggregate and interaggregate porosities and cake porosity were respectively predicted in contrast to the integrated variation of the relaxation ratio and the fractal dimension. Furthermore, a comparison between the model predictions of the cake pressure drop gradients with and without aggregate compression was conducted to validate the presence of cake collapse. The results show that the predictions based on the proposed collapse model are in agreement with the experiments, and the coordination number is one of the key factors that must be incorporated into the cake collapse models.

Airflow Simulation of an Umbrella Plate Scrubber

Airflow field of the umbrella plate scrubber was simulated through Fluent software of computational fluid dynamics (CFD) in which the calculation was based on kappa-epsiv model and SIMPLE algorithm. Equations were solved by the discrete methods. The inlet and outlet pressures were set as simulation initial values. The results show that the error between experiments and numerical simulation has not been more than 30% at the inlet some cross section, while at the outlet some cross section, the relative error is about 15%. Vortexes exist in entrance of the scrubber due to the increase of cubage. At the outlet of the scrubber, flow field is conspicuously changed due to the change of air orientation, and the umbrella plates have a great effect on the airflow turbulent. The total pressure change in the scrubber is inconspicuous. The results obtained from the simulative and experimental data have demonstrated that numerical simulation is an effective method for study the flow character of the umbrella plate scrubber.

Removal of copper and lead ions from aqueous solutions by adsorbent derived from sewage sludge

Adsorbent prepared from sewage sludge has been used for the adsorption of Cu 2+ and Pb 2+ from aqueous solutions. It was noted that an increase in removal efficiency achieved 72% and 56% when agitation time achieved 120 min, and a decrease in the removal efficiency from 81% and 70% to 36% and 40% when the heavy metals initial concentration from 10 mg L −1 to 80 mg L −1 for Cu 2+ and Pb 2+ concentration, the removal efficiency increased with the adsorbent concentration increased. The Langmuir model fitted the experimental data reasonably well. The adsorption capacities achieved 9.737 mg g −1 and 7.386 mg g −1 for the Cu 2+ and Pb 2+ , respectively. Desorption studies were performed by using dilute hydrochloric acid. Quantitative recovery of the metal ion is possible. The mechanism of adsorption seems to be ion exchange.