Co-combustion of municipal solid waste and coal gangue in a circulating fluidized bed combustor

Mixed incineration of municipal solid waste (MSW) in existing coal gangue power plant is a potentially highefficiency and low-cost MSW disposal way. In this paper, the co-combustion and pollutants emission characteristic of MSW and coal gangue was investigated in a circulating fluidized bed (CFB) combustor. The effect of MSW blend ratio, bed temperature and excess air ratio was detailedly studied. The results show the NOX and HC1 emission increases with the increasing MSW blend ratio and the SO2 emission decreases. With the increase of bed temperature, the CO emission decreases while the NOX and SO2 emission increases. The HC1 emission is nearly stable in the temperature range of 850-950℃. The increase of excess air ratio gradually increases the NOX emission but has no significant effect on the SO2 emission. The HC1 emission firstly increases and then decreases with the increase of excess air ratio. For a typical CFB operating condition with excess air ratio of 1.4, bed temperature of 900℃ and MSW blend ratio of 10%, the original CO, NOX, SO2 and HC1 emissions are 52, 181, 3373 and 58 mg/Nm^3 respectively.

Enhanced catalytic performance for direct synthesis of dimethyl ether from syngas over a La_2O_3 modified Cu-ZrO_2/γ-Al_2O_3 hybrid catalyst

A series of hybrid catalysts were made by physically mixing Cu-ZrO2 and γ-A12O3, for former it was modified with different loadings of La2O3 prepared by co-precipitation method. The catalysts were characterized by BET, XRD, N2O-adsorption, EXAFS, H2-TPR, NH3-TPD techniques and evaluated in the synthesis of dimethyl ether from syngas. The results show that La2O3 promoted catalysts displayed a significantly better catalytic performance compared with Cu-ZrO2#y-A12O3 catalyst in CO conversion and DME selectivity, and the optimum catalytic activity was obtained when the content of La2O3 was 12 wt%. The characterizations reveal that high copper dispersion, facile reducibility of copper particles and appropriate amount of acidic sites are responsible for the superior catalytic performance.

Synergistic oxidation-reforming of biomass for high quality syngas production based on a bifunctional catalyst

Conventional O_(2)gasification for low-rank biomass/sludge conversion is prone to high CO_(2)concentrations in the syngas because of its high O content and low calorific value.This study establishes a synergistic oxidationreforming reaction route for the conversion of low-rank carbon-containing resources into high-quality syngas.The efficient oxidation-reforming reaction is based on the bifunctional catalyst NiO-Fe_(2)O_(3)/Al_(2)O_(3),which includes Fe_(2)O_(3) oxidation sites and NiO reforming sites.Hydrogen temperature-programmed reduction,together with X-ray diffraction and X-ray photoelectron spectroscopy experiments,demonstrated that the two functional active sites have strong interactions with the support,leading to efficient cooperation between the oxidation reaction and reforming reaction with regards to both the reaction sequence and C/H/O element balance.Syngas produced from biomass/sludge based on oxidation-reforming reactions has an extremely low CO_(2)concentration of approximately 3%,and the valid gas(CO,H_(2))concentration exceeds 95%.The valid gas yield of walnut shell reached 1452.9 mL/g,the total gas yield was 1507.2 mL/g,and the H_(2)/CO ratio was 1.02,which are all very close to the theoretical maximum values of 1553.1 mL/g and 1.01,respectively,demonstrating that the inherent CO_(2)/H_(2)O along with CH4/tar species were efficiently converted to H_(2)and CO through oxidation-reforming reactions.During a 60-cycle test,NiO-Fe_(2)O_(3)/Al_(2)O_(3) exhibited good redox stability.