固定流量过程高浓度废水回用水网络设计

现有的水系统直观优化设计研究以新鲜水用量最小为目标,优先回用低浓度水源,考虑废水处理能力较少。文章基于多杂质固定流量问题,提出完全回用特殊高浓度水源的新方法——累积杂质负荷相减法(cumulative contaminant load reduction algorithm,CCLRA)。设计时,首先确定特殊高浓度水源及可回用该水源的需水流,然后从需水累积杂质负荷中除去该部分水源所含杂质负荷,最后按照关键杂质浓度由低到高的顺序回用其他水源。通过实例比较不同设计思路所得水网络,证明新方法设计过程简单,可兼顾高浓度水源回用和新鲜水用量最小目标,适用于含有其他工艺过程可消耗高浓度水源的水网络优化设计。

涉及固定流量用水单元的多杂质水网络直观设计方法

水网络集成是过程工业一项重要的节水技术,如今受到越来越多的关注。固定流量过程与固定杂质负荷过程是工业水网络中典型的两类操作过程。不同于固定杂质负荷过程,固定流量过程是一类不涉及传质的用水操作单元。改进了针对固定杂质负荷过程的多杂质用水系统提出的浓度势概念,并将其应用于固定流量过程的多杂质用水系统设计。设计中各过程的执行顺序由需求水流的浓度势(CPD)决定:按照CPD值由小到大的顺序依次执行各过程。满足需求水流时,按照虚拟分配量由大到小的顺序来选择内部水源,按照价格由低到高的顺序选择外部水源。实例结果表明,该方法只需简单计算即可获得多杂质固定流量水系统的设计网络。

The Flow Processes of Carbon Fixation Value of Typical Ecosystems

Based on data from ChinaFLUX this study analyzed the daily value flow processes of carbon fixation, monthly value distribution, and daily accumulative processes in a year of two kinds of typical forest, two kinds of grasses and a farmland. The results showed that the annual value of carbon fixation of these ecosystems was different, and flow processes and cumulative processes followed different trends over a year. The sequence of the five kinds of ecosystems based on the annual value of carbon fixation from largest to smallest was Yucheng warm temperate agriculture ecosystem （Yucheng）, Qianyanzhou subtropical artificial coniferous forest ecosystem （Qianyanzhou）, Changbai Mountain temperate mixed coniferous broad-leaved forest ecosystem （Changbaishan）, Haibei alpine meadow ecosystem （Haibei）and Dangxiong alpine meadow ecosystem （Dangxiong）. Variability in the daily and monthly carbon fixation at Qianyanzhou was the smallest, followed by Changbaishan, Yucheng, Dangxiong and Haibei. The cumulative processes of daily carbon fixation for the five kinds of ecosystems were well fitted to cubic curves.