A mathematical model was established to describe the direct reduction of pellets in a rotary hearth furnace （RHF）. In the model, heat transfer, mass transfer, and gas-solid chemical reactions were taken into account...A mathematical model was established to describe the direct reduction of pellets in a rotary hearth furnace （RHF）. In the model, heat transfer, mass transfer, and gas-solid chemical reactions were taken into account. The behaviors of iron metallization and dezincification were analyzed by the numerical method, which was validated by experimental data of the direct reduction of pellets in a Si-Mo furnace. The simulation results show that if the production targets of iron metallization and dezincification are up to 80% and 90%, respectively, the furnace temperature for high-temperature sections must be set higher than 1300~ C. Moreover, an undersupply of secondary air by 20% will lead to a decline in iron metallization rate of discharged pellets by 10% and a decrease in dezincing rate by 13%. In addition, if the residence time of pellets in the furnace is over 20 min, its further extension will hardly lead to an obvious increase in production indexes under the same furnace temperature curve.展开更多
The accuracy of three methods (pellet group count, inverse line transect method and track count) for estimat-ing the density of ungulate population was assessed, based on a wapiti population with the known size in the...The accuracy of three methods (pellet group count, inverse line transect method and track count) for estimat-ing the density of ungulate population was assessed, based on a wapiti population with the known size in the enclosure of500 hm2 on Tonghe Hunting Farm, Heilongjiang province, China, during 1992-1993. The estimation of population densityusing the Pelld group count method was the closeSt to the actual value, whereas the density of the wapiti population wasunderestimated by the inverse line transect method and overestimated by the track count method. No signilicant differenceexisted the estimated and actual values for the pellet group method and the inverse line transed method, but thesignificant differen was found for the track count method. Therefore, it is suggested that the pellet group method should begiven the priority in the survey of ungulate population abundance in practice.展开更多
This paper presents nonlinear ordinary differential equations (ODES) of the heavier pellets movement for two phase flow, which actually represent a system of equations. The usual methods of solution such as Runge -Kut...This paper presents nonlinear ordinary differential equations (ODES) of the heavier pellets movement for two phase flow, which actually represent a system of equations. The usual methods of solution such as Runge -Kutta method and it's datum results are discussed. This paper solves ODES of general form using variable mesh-length, linearizing the nonlinear terms by finite analysis method, fuilding an iteration sequence, and amending the nonlinear terms by iteration . The conditions of convergent operation of iteration solution is checked. The movement orbit and velocity of the pellets are calculated. Analysis of research results and it's application examples are illustrated.展开更多
The preservation methods of polyurethane immobilized nitrifying bacteria pellets which had been enriched in laboratory were provided. Factors such as temperature, pH and light, which affect the nitrification activity ...The preservation methods of polyurethane immobilized nitrifying bacteria pellets which had been enriched in laboratory were provided. Factors such as temperature, pH and light, which affect the nitrification activity of polyurethane immobilized pellets, were investigated. The result showed that dark, deionized water and low temperature is suitable for polyurethane immobilized nitrifying bacteria pellets’ long term preservation.展开更多
基金financially supported by the National Key Basic Research and Development Program of China(No. 2012CB720405)
文摘A mathematical model was established to describe the direct reduction of pellets in a rotary hearth furnace （RHF）. In the model, heat transfer, mass transfer, and gas-solid chemical reactions were taken into account. The behaviors of iron metallization and dezincification were analyzed by the numerical method, which was validated by experimental data of the direct reduction of pellets in a Si-Mo furnace. The simulation results show that if the production targets of iron metallization and dezincification are up to 80% and 90%, respectively, the furnace temperature for high-temperature sections must be set higher than 1300~ C. Moreover, an undersupply of secondary air by 20% will lead to a decline in iron metallization rate of discharged pellets by 10% and a decrease in dezincing rate by 13%. In addition, if the residence time of pellets in the furnace is over 20 min, its further extension will hardly lead to an obvious increase in production indexes under the same furnace temperature curve.
文摘The accuracy of three methods (pellet group count, inverse line transect method and track count) for estimat-ing the density of ungulate population was assessed, based on a wapiti population with the known size in the enclosure of500 hm2 on Tonghe Hunting Farm, Heilongjiang province, China, during 1992-1993. The estimation of population densityusing the Pelld group count method was the closeSt to the actual value, whereas the density of the wapiti population wasunderestimated by the inverse line transect method and overestimated by the track count method. No signilicant differenceexisted the estimated and actual values for the pellet group method and the inverse line transed method, but thesignificant differen was found for the track count method. Therefore, it is suggested that the pellet group method should begiven the priority in the survey of ungulate population abundance in practice.
文摘This paper presents nonlinear ordinary differential equations (ODES) of the heavier pellets movement for two phase flow, which actually represent a system of equations. The usual methods of solution such as Runge -Kutta method and it's datum results are discussed. This paper solves ODES of general form using variable mesh-length, linearizing the nonlinear terms by finite analysis method, fuilding an iteration sequence, and amending the nonlinear terms by iteration . The conditions of convergent operation of iteration solution is checked. The movement orbit and velocity of the pellets are calculated. Analysis of research results and it's application examples are illustrated.
文摘The preservation methods of polyurethane immobilized nitrifying bacteria pellets which had been enriched in laboratory were provided. Factors such as temperature, pH and light, which affect the nitrification activity of polyurethane immobilized pellets, were investigated. The result showed that dark, deionized water and low temperature is suitable for polyurethane immobilized nitrifying bacteria pellets’ long term preservation.
