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Salt management in irrigated agriculture is critical to the economies of the San Joaquin Valley of California and many other areas around the world. Purified salts can be recovered as marketable products through fractional crystallization following concentration of final stage drainage water from integrated on-farm drainage management systems. To obtain recovered salt and use as a commercial product, new systems which can perform with higher efficiency and lower environmental impact than solar evaporation basins or solar ponds that have previously been used for the final stage are in need of development. For this purpose, a number of solar-assisted brine concentration concepts have been explored, including an open liquid film-type using a tilted evaporation surface described here. Model performance was conceptually evaluated and then experimentally verified.A transient model was developed from energy and component mass balances and employed constitutive heat and mass transfer relationships from various other sources for simulating concentration of agricultural drainage water using a liquid film solar-assisted concentrator.Measured maximum evaporation rate and productivity were between 1.3 and 1.5 kg m−2 h−1, and 80 kg m−2 over a 7 day experimental period respectively which was about a third better performance compared with a shallow basin horizontal concentrator. Measurements were in good agreement with model predictions: within 2 °C at the peak and 4 °C at the lowest evaporation, and 0.2 kg m−2 h−1 for evaporation rates during the peak evaporation periods of the day when compared with independent data sets. Cumulative evaporation rates were from 75 to 85 kg m−2 for the tilted concentrator model and 60 to 65 kg m−2 for the horizontal concentrator model after 7 days. The tilted concentrator yielded productivity and efficiency that were 33% higher than the horizontal concentrator according to the experimental result for the same period and location. 相似文献
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The feasibility of biologically removing methanol from kraft pulp mill evaporator condensate was investigated, using a high temperature membrane bioreactor (MBR). Over the range of temperatures investigated (55–70°C), a mixed culture of methanol-utilizing microorganisms could be successfully developed, using synthetic condensate as a feedstock. A maximum specific methanol utilization coefficient of approximately 0.81 day−1 occurred at an operating temperature of 60°C. Over 99% of the methanol was removed from the condensate at operating temperatures of 55 and 60°C. Above 60°C, the specific methanol utilization coefficient declined sharply, indicating that at high operating temperatures, the inactivating effect of temperature on the mixed culture of microorganisms must be considered. A relatively simple model was proposed and used to estimate the effect of high temperatures on methanol removal kinetics in an MBR over the range of temperatures investigated. The operating temperature also had a significant effect on the observed growth yield. At increasing operating temperatures, a larger fraction of the methanol consumed was converted to energy, reducing the observed growth yield. 相似文献
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分析宁夏南部山区淀粉生产废水资源化需求及季节性生产、高水质大用水量、低温环境等多个生产影响因素,选择以四效减压蒸发技术为核心的废水再循环流程;采用可扩充和可重用的计算机辅助设计手段,通过再循环流程主要参数及所需工艺设备的计算与选型,设计结果达到蒸汽经济性较高的目的,可为解决淀粉生产缺水和污染提供技术参考。 相似文献
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在蒸发操作过程中,蒸发室的液位稳定十分重要,现在液位的检测一般采用目镜观察法,随着蒸发技术的发展,这种方法已不能满足需要。本通过对几种液位检测法的分析,重点介绍一种实用的液位检测法。 相似文献
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Һ����Ȼ��(LNG)�۳�����ѹ����ʽ����������Ƽ��� 总被引:1,自引:1,他引:0
由于地理、用户使用条件和峰段要求的限制,LNG槽车在输送天然气方面有着巨大的市场需求,是管道输配的重要补充手段。LNG槽车往往需要在没有机械动力的情况下,依靠配套的增压汽化器提供压力源,采用顶部气相空间加压方式卸载液体。槽车常配用的汽化器有空温式汽化器和水浴式汽化器两种形式,空温式汽化器使用空气作为热源,节约能源,操作费用低廉。对于长江三角洲地区,常年气候温和湿润,最低气温在零度以下的天数屈指可数,使用空湿式气化器完全满足生产要求。文章介绍LNG槽车自增压空温式汽化器的设计计算,其中包括天然气气相和液相物性的计算方法,以及空温式汽化器的热力计算。然后给出空温式汽化器的换热面积和结构尺寸等设计参数。 相似文献
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