In this paper, ultrasonic-enhanced replacement of lead by zinc in lead leaching solution was studied. The effects of reaction time, rotational speed, temperature, concentration of leaching solution and the ratio of the surface area of the zinc plate immersed in the leaching solution to the volume of leaching solution (S : V) were studied under both conventional and ultrasonic conditions. The optimum ultrasonic-assisted replacement conditions were as follows: the S : V of 0.04 (4 cm 2 100 ml −1 ), reaction temperature of 30°C, replacement time of 30 min and the concentration of leaching solution is 5 g l −1 , leading to a lead replacement rate of 94.84%. Compared with the conventional replacement process, the reaction time of ultrasonic-enhanced substitution could be reduced to one half, and the demand of reaction temperature, leaching solution concentration and other conditions were decreased accordingly. Introducing ultrasonic into the replacement reaction is promising to reduce the energy consumption in the hydrometallurgical industry also caters to the demands of environment protection.
Based on the recycle split vapor (RSV) process for ethane recovery, this paper proposes three primary improved processes, and in China, five rich feed compositions are selected as preliminary data. We use economic and thermodynamic analysis methods to compare and analyze RSV and its improved processes comprehensively. The comparative analysis results show that: ①The enhanced techniques all show a certain energy-saving effect, especially it is evident for the modified recycle split vapor with liquid flashing (RSVF) process to save energy; ②The geometric structure of the plate-fin heat exchanger inside the cold box significantly affects its capital cost, the design of the plate-fin heat exchanger in the corresponding cold box is basically the same, with slight differences under different feed conditions; ③The compressors and expander are the most prominent investment types of equipment, and their purchase costs accounting for about 70% of the total purchased equipment costs. The values of financial net present value (FNPV) of the improved processes are all greater than zero under the operating conditions in this study, which can meet the profitability required by the benchmark rate of return. The project has a more significant return on investment and shorter return time; ④The improved processes under five feeds show excellent performance and adaptability: the larger GPM (gallons per thousand cubic feet) values of feed compositions, the more apparent the energy saving. The main contributors to the exergy destruction are towers, compressors, expander, and cold boxes; ⑤Compared with the improved recycle split vapor with gas extraction (RSVG) and supplemental rectification with compression and recycle split vapor (SRCR) processes, the improved RSVF process has a better pre-separation effect for heavy hydrocarbons by adding a flash separator, which makes this process have less exergy destruction and enormous energy-saving potential.
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