The recovery of contaminants and useful substances from liquid wastes, thepurification of production effluents and the separation of thermally instable mixtures are some ofthe multivarious applications of thin-film di...The recovery of contaminants and useful substances from liquid wastes, thepurification of production effluents and the separation of thermally instable mixtures are some ofthe multivarious applications of thin-film distillers in many processes of the chemical and alliedindustries and of the food industries. In a study carried out in pilot plants with distillation testsystems there was found a good agreement between the experimental separation results and thoseobtained by computing with a theorectical model; the latter is based on the assumption of phaseequilibrium between the vapour formed on an infinitely small element of area in a liquid film of anygiven concentric periphery of the vertically arranged evaporator. These tests were perfomed undervarious phase loads.展开更多
In many chemical processes, large amounts of wastewater containing butanol and isobutanol are produced.Given that n-butanol-isobutanol-water can form triple azeotrope, high-purity butanol cannot be recovered from the ...In many chemical processes, large amounts of wastewater containing butanol and isobutanol are produced.Given that n-butanol-isobutanol-water can form triple azeotrope, high-purity butanol cannot be recovered from the wastewater by ordinary distillation. To economically and effectively recover butanol from this kind of wastewater, 1,4-butanediol is selected as an extractant to break the formation of the azeotropes, and a doubleeffect extractive distillation process is proposed. The conceptual design of the proposed process is accomplished based on process simulation. With the proposed process, the purity of recovered butanol and water is greater than 99.99 wt%. In comparison with the conventional azeotropic distillation process, economic analysis shows that the operating cost of the proposed process is lower: when the capacity of wastewater treatment is 100 t·h^(-1), the total operating cost decreases by 5.385 ×10~6 USD per year, and the total annual cost of the new process decreases by 5.249 ×10~6 USD per year. In addition, in the extractive distillation system, variable effects on separation purities and cost are more complex than those in the ordinary distillation system. The method and steps to optimize the key variables of the extractive distillation system are also discussed in this paper and can provide reference for similar studies.展开更多
The effects of feed temperature and pH value on the removal of aqueous phenol wastewater by vacuum membrane distillation process are studied by experiments employing micro porous membranes of poly vinylidene fluoride ...The effects of feed temperature and pH value on the removal of aqueous phenol wastewater by vacuum membrane distillation process are studied by experiments employing micro porous membranes of poly vinylidene fluoride (PVDF) and ploy tetrafluoro ethylene (PTFE) with nominal average pore sizes 0.22 mm and 0.20 mm, respectively. It is found that the optimal feed temperature for PVDF membrane is 50 ℃; and for PTFE membrane, 60 ℃. The pH value of the feed has little influence on the membrane fluxes and ion rejection ratios, while it influenced considerably on the selectivity. Increase of pH value of the feed is conducive to the increase of selectivity. In the same experimental conditions, PTFE membrane shows better separation performance than PVDF membrane does.展开更多
A new operation policy--quasi-batch distillation for recovering infinitesimal amounts species existing in a mixture is presented. In quasi-batch distillation operation, feed is introduced with a constant flow rate ont...A new operation policy--quasi-batch distillation for recovering infinitesimal amounts species existing in a mixture is presented. In quasi-batch distillation operation, feed is introduced with a constant flow rate onto the feed stage of the column, and the flow rate of the distillate is the same as that of the feed, whereas the bottom product is withdrawn periodically. The behavior of quasi-batch distillation is simulated and analyzed through an example on heavy water separation. Comparing with continuous or batch distillation, the new operation policy is more reliable and efficient to achieve higher recovery of dilute component. This is especially suitable for separating small amount of precious species from large amount of raw material.展开更多
文摘The recovery of contaminants and useful substances from liquid wastes, thepurification of production effluents and the separation of thermally instable mixtures are some ofthe multivarious applications of thin-film distillers in many processes of the chemical and alliedindustries and of the food industries. In a study carried out in pilot plants with distillation testsystems there was found a good agreement between the experimental separation results and thoseobtained by computing with a theorectical model; the latter is based on the assumption of phaseequilibrium between the vapour formed on an infinitely small element of area in a liquid film of anygiven concentric periphery of the vertically arranged evaporator. These tests were perfomed undervarious phase loads.
基金Supported by the National Key Technology Support Program of China(2014BAC10B01)the National Natural Science Foundation of China(21406123)the Key Scientific and Technological Project of Shanxi Province(MH2014-10)
文摘In many chemical processes, large amounts of wastewater containing butanol and isobutanol are produced.Given that n-butanol-isobutanol-water can form triple azeotrope, high-purity butanol cannot be recovered from the wastewater by ordinary distillation. To economically and effectively recover butanol from this kind of wastewater, 1,4-butanediol is selected as an extractant to break the formation of the azeotropes, and a doubleeffect extractive distillation process is proposed. The conceptual design of the proposed process is accomplished based on process simulation. With the proposed process, the purity of recovered butanol and water is greater than 99.99 wt%. In comparison with the conventional azeotropic distillation process, economic analysis shows that the operating cost of the proposed process is lower: when the capacity of wastewater treatment is 100 t·h^(-1), the total operating cost decreases by 5.385 ×10~6 USD per year, and the total annual cost of the new process decreases by 5.249 ×10~6 USD per year. In addition, in the extractive distillation system, variable effects on separation purities and cost are more complex than those in the ordinary distillation system. The method and steps to optimize the key variables of the extractive distillation system are also discussed in this paper and can provide reference for similar studies.
文摘The effects of feed temperature and pH value on the removal of aqueous phenol wastewater by vacuum membrane distillation process are studied by experiments employing micro porous membranes of poly vinylidene fluoride (PVDF) and ploy tetrafluoro ethylene (PTFE) with nominal average pore sizes 0.22 mm and 0.20 mm, respectively. It is found that the optimal feed temperature for PVDF membrane is 50 ℃; and for PTFE membrane, 60 ℃. The pH value of the feed has little influence on the membrane fluxes and ion rejection ratios, while it influenced considerably on the selectivity. Increase of pH value of the feed is conducive to the increase of selectivity. In the same experimental conditions, PTFE membrane shows better separation performance than PVDF membrane does.
基金Supported by the National Natural Science Foundation of China (No. 20136010).
文摘A new operation policy--quasi-batch distillation for recovering infinitesimal amounts species existing in a mixture is presented. In quasi-batch distillation operation, feed is introduced with a constant flow rate onto the feed stage of the column, and the flow rate of the distillate is the same as that of the feed, whereas the bottom product is withdrawn periodically. The behavior of quasi-batch distillation is simulated and analyzed through an example on heavy water separation. Comparing with continuous or batch distillation, the new operation policy is more reliable and efficient to achieve higher recovery of dilute component. This is especially suitable for separating small amount of precious species from large amount of raw material.
