DISTRIBUTED DISCHARGE OF COOLING WATER ALONG DIRECTION OF STREAM FLOW1

ABSTRACT. A multiple-outfall system for cooling water disposal which is distributed along the direction of stream flow is analyzed. The results provide a simple method of preliminary design of a cooling water discharge outfall system and for a quick extimate of water quality of a polluted stream. It is shown that a properly designed distributed discharge system is capable of preventing serious pollution due to localized discharge of wastes and waste heat; however, the final design of the discharge system should take into account alternative schemes of waste heat disposal and their economic consequences.     

ECOLOGICAL MANAGEMENT PROBLEMS CAUSED BY HEATED WASTE WATER DISCHARGE INTO THE AQUATIC ENVIRONMENT1

Discharge of heated waste water may affect the entire aquatic ecosystem–the interrelated biological, chemical, physical system–and, if the temperature change is large, may destroy the capacity of the ecosystem to serve a variety of beneficial purposes. However, it is possible to discharge heated waste water in carefully controlled amounts without seriously degrading the aquatic ecosystem. There are four basic alternatives which are open to us with regard to the heated waste water problem which we may choose singly or in various combinations: (1) Placing all heated, waste water in streams, lakes, and oceans without regard to the effects. Thus considering the environmental damage as a necessary consequence of our increased power demand. (2) Using, but not abusing, existing ecosystems. This means regulating the heated waste water discharge to fit the receiving capacity of the ecosystem. (3) Finding alternative ways to dissipate or beneficially use waste heat. (4) Modifying ecosystems to fit the new temperature conditions. We are all dependent upon a life-support system which is partly industrial and partly ecological. Unfortunately, we have reached a stage of development where the non-expandable, ecological portion of our life-support system is endangered by the expanding industrial portion. Optimal function and full beneficial use of both portions of our life-support system will only be possible if a variety of disciplines and diverse points of view can cooperate and work together effectively. Since wastes in amounts that are acceptable taken one at a time may be lethal collectively, environmental management should be on a regional basis.     

DIGITAL SIMULATION OF THE EFFECT OF THERMAL DISCHARGE ON STREAM WATER QUALITY1

A modified transient version of the Streeter-Phelps model along with the energy balance equation is employed to analyze the effects of waste heat discharge from power plants on stream water quality. Analysis is also made to examine the effects of the upstream water quality and stream velocity on the downstream DO concentration level. The resulting coupled nonlinear hyperbolic partial differential equations representing the energy, BOD and DO concentrations are solved by the method of characteristics and simulated on a digital computer. Final numerical results indicate that the allowable quantity of thermal discharge does heavily depend on the upstream quality.     

Short-term wind speed forecasting based on random forest model combining ensemble empirical mode decomposition and improved harmony search algorithm

ABSTRACT

Wind speed forecasting plays an important role in power grid dispatching management. This article proposes a short-term wind speed forecasting method based on random forest model combining ensemble empirical modal decomposition and improved harmony search algorithm. First, the initial wind speed data set is decomposed into several ensemble empirical mode functions by EEMD, then feature extraction of each sub-modal IMF is performed using fast Fourier transform to solve the cycle of each sub-modal IMF. Next, combining the high-performance parameter optimization ability of the improved harmony search algorithm, two optimal parameters of random forest model, number of decision trees, and number of split features are determined. Finally, the random forest model is used to forecast the processing results of each submodal IMF. The proposed model is applied to the simulation analysis of historical wind data of Chaoyang District, Liaoning Province from April 27, 2015 to May 22, 2015. To illustrate the suitability and superiority of the EEMD-RF-IHS model, three types of models are used for comparison: single models including ANN, SVM, RF; EMD combination models including EMD-ANN, EMD-SVM, EMD-RF; EEMD combination models including EEMD-ANN, EEMD-SVM, EEMD-RF. The analysis results of evaluation indicators show that the proposed model can effectively forecast short-term wind data with high stability and precision, providing a reference for forecasting application in other industry fields.     

锚索拉断火花引爆瓦斯的实验研究

设计了锚索拉断火花引爆瓦斯实验装置 ,在瓦斯浓度为爆炸范围的环境中 ,对锚索拉断时产生火花规律及引起瓦斯爆炸的可能性进行了一系列实验研究。结果表明 :锚索拉断产生火花的概率为 5 0 % ,锚索钢绞线破断产生的火花不能引起瓦斯爆炸。采用红外热成象仪对锚索拉断火花温度的测试表明 ,锚索拉断产生的火花最高温度远小于瓦斯爆炸所需的最低点燃温度 6 5 0℃。     

THERMAL GRADIENTS IN RIVERS AND RESERVOIRS DUE TO HEATED PLANT EFFLUENTS1

ABSTRACT The direction of heated effluents from large thermal power plants into streams and lakes has been a matter of public concern for some time, and the collection of prototype data related to the hydraulic aspects has taken on massive proportions. Unfortunately, most of the data are proprietary and not available for public analysis. The authors have endeavored to collect such data as are available to them for the initiation of steps toward generalization and the discussion of some of the more evident hydraulic considerations. The study is primarily concerned with rivers, including estuaries, with some interest in cooling ponds.     

Catalytic decomposition of hydrocarbon into hydrogen and carbon in a spouted-bed reactor as the second-stage reactor of a plastic recycling process

A two-stage process for the chemical recycling of plastics is proposed. In this process, which consists of two reactors, plastics are converted into hydrogen and carbon. In the first reactor, plastic chips are thermally decomposed into hydrocarbons. In the second reactor, the hydrocarbons formed in the first reactor are catalytically decomposed into carbon and hydrogen. In this study, in order to obtain basic data for the second reactor, propene was catalytically decomposed in a laboratory-scale spouted-bed reactor (600mm high, 21.6mm internal diameter, made of SUS304). The effect of the type of spouting medium used on the decomposition behavior of propene was investigated using four types of spouting medium (nickel-plated -alumina, palladium-plated -alumina, nickel-impregnated -alumina, and -alumina). The nickel-impregnated -alumina gave the best propene conversion and hydrogen yield.     

火灾中双层窗玻璃破裂机理的研究

把单层窗玻璃破裂的模型作为研究基础,基于原有的单层窗玻璃破裂的计算软件开发设计了双层窗玻璃破裂的模型,并对双层玻璃的内表面及其空隙的热传递过程和连续发生的玻璃破裂机理进行了研究。     

Lowest Effect Levels of Lead and Mercury on Decomposition of Mor Layer Samples in a Long-Term Experiment

Indications of possible negative effects of lead (Pb) and mercury(Hg) on microbial respiration in Southern Swedish forest humus layers led to experiments on dose-response relationships by additions of metal salts in the laboratory. Respiration rates andweight loss due to decomposition of organic material were measured. For relevance to field situations metal doses were low,the time span was long, 550 days including freeze storage, and microbial activity was kept up by plant litter additions. We looked for effects of Pb and Hg at levels moderately elevated above the Southern Swedish reference, as well as combined effectsof Pb + Hg. A reduction in respiration and decomposition of10% was found at about 225–245 g g^-1 of total Pb, i.e. ata Pb level elevated 3.5 times. Although small effects of Hg werefound even at the lowest dose level, 10% inhibition of microbialactivity appeared temporarily at about 2–3 g g^-1 of total Hg, i. e. at 6–8 times the reference level. There were nolong-term additive effects of Pb and Hg on decomposition. Type of anion had a strong influence on the test, chlorides of Pbbeing more toxic than nitrates. Long-term monitoring and maintenance of microbial activity during the experiment were prerequisites for the occurrence of effects at low metal levels.     

火电厂FGD装置性能试验有关问题的探讨

针对目前我国还没有专门针对烟气脱硫(FGD)装置性能试验规程的情况,对于火电厂FGD性能试验的内容和标准、现场测量的特点、测点布置和测量方法的选择、试验工况和试验时间的要求等问题,进行了介绍和探讨,以期为脱硫装置性能试验的实践提供一些建议和参考.