In order to study the effect of agitation on the characteristics of air dense medium fluidization, we designed and constructed an agitation device. Analyses were then conducted on the fluidization characteristics curv...In order to study the effect of agitation on the characteristics of air dense medium fluidization, we designed and constructed an agitation device. Analyses were then conducted on the fluidization characteristics curves, the bed density stability and the average bubble rise velocity Uaunder different agitation conditions. The results indicated that a lower bed pressure drop(without considering lower gas velocity in a fixed bed stage) and higher minimum fluidized velocity are achieved with increasing agitation speed.The height d(distance between the lower blades and air distribution plate) at which the agitation paddle was located had a considerable effect on the stability of the bed density at 9.36 cm/s < U < 10.70 cm/s. The higher the value of d, the better the stability, and the standard deviation of the bed density fluctuation r dropped to 0.0364 g/cm^3 at the ideal condition of d = 40 mm. The agitation speed also had a significant influence on the fluidization performance, and r was only 0.0286 g/cm^3 at an agitation speed of N = 75 r/min. The average bubble rise velocity decreased significantly with increasing agitation speed under the operating condition of 1.50 cm/s < U–U_(mf)< 3.50 cm/s. This shows that appropriate agitation contributes to a significant improvement in the fluidization quality in a fluidized bed, and enhances the separation performance of a fluidized bed.展开更多
The IrTe2 transition metal dichalcogenide un- dergoes a series of structural and electronic phase transi- tions when doped with Pt. The nature of each phase and the mechanism of the phase transitions have attracted mu...The IrTe2 transition metal dichalcogenide un- dergoes a series of structural and electronic phase transi- tions when doped with Pt. The nature of each phase and the mechanism of the phase transitions have attracted much attention. In this paper, we report scanning tunneling mi- croscopy and spectroscopy studies of Pt-doped IrTe2 with varied Pt contents. In pure IrTe2, we find that the ground state has a 1/6 superstructure, and the electronic structure is inconsistent with Fermi surface nesting-induced charge density wave order. Upon Pt doping, the crystal structure changes to a 1/5 superstructure and then to a quasi-periodic hexagonal phase. First-principles calculations show that the superstructures and electronic structures are determined by the global chemical strain and local impurity states that can be tuned systematically by Pt doping.展开更多
基金financial support by the National Key Programs for Fundamental Research and Development of China(No.2012CB214904)the National Natural Science Foundation of China(Nos.51174203,51134022)
文摘In order to study the effect of agitation on the characteristics of air dense medium fluidization, we designed and constructed an agitation device. Analyses were then conducted on the fluidization characteristics curves, the bed density stability and the average bubble rise velocity Uaunder different agitation conditions. The results indicated that a lower bed pressure drop(without considering lower gas velocity in a fixed bed stage) and higher minimum fluidized velocity are achieved with increasing agitation speed.The height d(distance between the lower blades and air distribution plate) at which the agitation paddle was located had a considerable effect on the stability of the bed density at 9.36 cm/s < U < 10.70 cm/s. The higher the value of d, the better the stability, and the standard deviation of the bed density fluctuation r dropped to 0.0364 g/cm^3 at the ideal condition of d = 40 mm. The agitation speed also had a significant influence on the fluidization performance, and r was only 0.0286 g/cm^3 at an agitation speed of N = 75 r/min. The average bubble rise velocity decreased significantly with increasing agitation speed under the operating condition of 1.50 cm/s < U–U_(mf)< 3.50 cm/s. This shows that appropriate agitation contributes to a significant improvement in the fluidization quality in a fluidized bed, and enhances the separation performance of a fluidized bed.
基金supported by the National Natural Science Foundation and Ministry of Science and Technology of China(2011CB921901,2011CB921701,2012CB821403,and 2015CB921000)
文摘The IrTe2 transition metal dichalcogenide un- dergoes a series of structural and electronic phase transi- tions when doped with Pt. The nature of each phase and the mechanism of the phase transitions have attracted much attention. In this paper, we report scanning tunneling mi- croscopy and spectroscopy studies of Pt-doped IrTe2 with varied Pt contents. In pure IrTe2, we find that the ground state has a 1/6 superstructure, and the electronic structure is inconsistent with Fermi surface nesting-induced charge density wave order. Upon Pt doping, the crystal structure changes to a 1/5 superstructure and then to a quasi-periodic hexagonal phase. First-principles calculations show that the superstructures and electronic structures are determined by the global chemical strain and local impurity states that can be tuned systematically by Pt doping.
