The fact that water requirements are a major problem for present and future developments in material beneficiation, and the construction of a new power plant in South Africa, forms the basis for the utilization of a R...The fact that water requirements are a major problem for present and future developments in material beneficiation, and the construction of a new power plant in South Africa, forms the basis for the utilization of a Rotary Triboelectrostatic Separator (RTS) for beneficiation of South African pulverized coal. The cleaning potential of Majuba and Koorfontein coal was first evaluated using kinetic froth flotation tests on the -177 μm coal fraction. The RTS tests were conducted under varied process parameters. Parameters such as applied separating voltage, air injection velocity, particle feed rate and splitter position were investigated. Two stage separation results show that the RTS reduced Majuba coal initially containing about 30% ash to a clean product of 14.30%, or 19.46%, ash at a combustible recovery of 15.10%, or 53.02%, respectively. Similar separation performance was also achieved with the Koorfontein coal. The mineral and organic compositions in the feed, after single stage and after the second stage separations were characterized using X-ray diffraction analysis. The results show a better separation for the second stage coal products.展开更多
PEM （Proton Exchange Membrane） fuel cell is a promising renewable energy source to a wide range of applications for its clean products and high power density. However, controlling its humidity is a challenging probl...PEM （Proton Exchange Membrane） fuel cell is a promising renewable energy source to a wide range of applications for its clean products and high power density. However, controlling its humidity is a challenging problem due to the interdependence of several phenomena contributing in membrane＇s water content. This work deals with efficiency improvement of PEM fuel cells via humidity control. An innovative strategy of control based on the model of Ref. [1] is proposed. It consists on regulating gas humidification rates according to the power demand so that to minimize power losses. The proposed control takes into consideration constraints related to humidification in order to avoid dry out or flooding of the membrane. Simulations results show that time-phasing between hydrogen and oxygen humidification rates plays an important role in minimizing power losses. The proposed control shows significant improvement in the fuel cell＇s efficiency up to 20%.展开更多
Naphtha is an important raw material for manufacture of clean fuels and ethylene products. However, China is experiencing a serious imbalance between supply and demand of naphtha, due to its rapidly increasing car pop...Naphtha is an important raw material for manufacture of clean fuels and ethylene products. However, China is experiencing a serious imbalance between supply and demand of naphtha, due to its rapidly increasing car population and booming ethylene industry, the demand of which cannot be met by the domestic depleting crude oil resources. Focusing on alleviating the above-mentioned naphtha deficit, this paper puts forward an idea suggesting that China＇s limited naphtha resource should be used reasonably. Naphtha feedstocks with more potential aromatic content should be used in catalytic reforming process to produce clean fuel products, and those feedstocks with more paraffinic content should be used in ethylene production. Meanwhile, industry tests show that the low-valued naphtha byproduct from ethylene plants and the products of secondary processing units at refineries can also be applied so as to extend the naphtha supply for manufacture of cleaner fuels and ethylene derivatives.展开更多
The formation of kitchen greasy dirt was expounded, and the different types of kitchen cleaner and common products were introduced. At last, the development trend for kitchen cleaner was prospected.
基金the financial support of the South African National Energy Research Institute (SANERI)
文摘The fact that water requirements are a major problem for present and future developments in material beneficiation, and the construction of a new power plant in South Africa, forms the basis for the utilization of a Rotary Triboelectrostatic Separator (RTS) for beneficiation of South African pulverized coal. The cleaning potential of Majuba and Koorfontein coal was first evaluated using kinetic froth flotation tests on the -177 μm coal fraction. The RTS tests were conducted under varied process parameters. Parameters such as applied separating voltage, air injection velocity, particle feed rate and splitter position were investigated. Two stage separation results show that the RTS reduced Majuba coal initially containing about 30% ash to a clean product of 14.30%, or 19.46%, ash at a combustible recovery of 15.10%, or 53.02%, respectively. Similar separation performance was also achieved with the Koorfontein coal. The mineral and organic compositions in the feed, after single stage and after the second stage separations were characterized using X-ray diffraction analysis. The results show a better separation for the second stage coal products.
文摘PEM （Proton Exchange Membrane） fuel cell is a promising renewable energy source to a wide range of applications for its clean products and high power density. However, controlling its humidity is a challenging problem due to the interdependence of several phenomena contributing in membrane＇s water content. This work deals with efficiency improvement of PEM fuel cells via humidity control. An innovative strategy of control based on the model of Ref. [1] is proposed. It consists on regulating gas humidification rates according to the power demand so that to minimize power losses. The proposed control takes into consideration constraints related to humidification in order to avoid dry out or flooding of the membrane. Simulations results show that time-phasing between hydrogen and oxygen humidification rates plays an important role in minimizing power losses. The proposed control shows significant improvement in the fuel cell＇s efficiency up to 20%.
文摘Naphtha is an important raw material for manufacture of clean fuels and ethylene products. However, China is experiencing a serious imbalance between supply and demand of naphtha, due to its rapidly increasing car population and booming ethylene industry, the demand of which cannot be met by the domestic depleting crude oil resources. Focusing on alleviating the above-mentioned naphtha deficit, this paper puts forward an idea suggesting that China＇s limited naphtha resource should be used reasonably. Naphtha feedstocks with more potential aromatic content should be used in catalytic reforming process to produce clean fuel products, and those feedstocks with more paraffinic content should be used in ethylene production. Meanwhile, industry tests show that the low-valued naphtha byproduct from ethylene plants and the products of secondary processing units at refineries can also be applied so as to extend the naphtha supply for manufacture of cleaner fuels and ethylene derivatives.
基金National Natural Science Foundation of China(NSFC)(No.41171250)
文摘The formation of kitchen greasy dirt was expounded, and the different types of kitchen cleaner and common products were introduced. At last, the development trend for kitchen cleaner was prospected.
