深基坑降水施工中防止相邻建筑沉降的技术措施

本文结合漳州银冠大厦基坑护壁降水的工程实例,论述了基坑与邻近建筑物距离过近时,采用截水帷幕,改基坑边缘井为内部井以调整降水曲线和配合回灌等三项措施,确保相邻建筑不发生沉降。     

Measurement of additional shear during sludge conditioning and dewatering

Optimum polymer dose is influenced both by the polymer demand of the sludge and the shear applied during conditioning. Sludge exposed to additional shear following conditioning will experience a decrease in cake solids concentration for the same polymer dose. Therefore, it is necessary to measure or quantify the additional shear in order to optimize the conditioning and dewatering. There is currently no direct or indirect method to achieve this. The main objective of this study was to develop a method based on torque rheology to measure the amount of shear that a sludge network experiences during conditioning and dewatering. Anaerobically digested sludge samples were exposed to increasing levels of mixing intensities and times, and rheological characteristics of samples were measured using a torque rheometer. Several rheological parameters were evaluated including the peak torque and totalized torque (area under the rheograms). The results of this study show that at the optimum polymer dose, a linear relationship exists between the applied shear and the area under the rheograms, and this relationship can be used to estimate an unknown amount of shear that the sludge was exposed to. The method is useful as a research tool to study the effect of shear on dewatering but also as an optimization tool in a dewatering automation system based on torque rheology.     

THE EFFECTS OF IMPROVING SEWAGE SLUDGE DIGESTION

A model was developed and tested to investigate the effects of various parameters on the processing costs of anaerobic digestion. The model was based on empirical data collected from full-scale plants which varied in size from 35,000 to 900,000 population equivalents. (Equivalent to loading rates of 0.5 to 2.7 kg VS/m³/d.) In spite of different operating regimes and conditions of the plants analysed, various relationships were discovered between: sludge quality and volatile solids destruction; sludge quality and biogas yield; and, effluent volatile solids and dewatering. Where correlations existed, these were used to make predictions on operating costs of the digestion and dewatering plant based on sensitivity analysis. The results of the model were used to make recommendations on how to optimise the operation of an anaerobic digestion plant.     

原油脱盐脱水技术评述

综述了各种非电脱盐技术方法 ,主要包括离心法、直流电型旋流分离、过滤法、旋流分离、声化学法、磁处理及微波辐射等。同时指出 ,旋流分离技术在原油脱盐脱水领域具有很好的经济效益和广阔的应用前景。     

我国细粒煤脱水技术与设备研究现状

搞好细粒煤分选是生产洁净煤的重要途径,选煤厂出厂产品水分的高低直接受细粒煤水分高低的影响。本文就加强细粒煤脱水的重要性进行论述,并介绍了近期研制成功的应用于工业生产的细粒煤脱水技术与设备     

阳春硫铁矿疏干及地表塌陷

广东省阳春硫铁矿矿区水文地质条件复杂,围岩富含岩溶水,为整治地下涌水,采取了一系列措施对井下和地表进行治理。详细介绍了生产疏干放水与地表塌陷的情况,对存在的问题提出了探索性建议。     

Shear Strength Equations for Unsaturated Soil under Drying and Wetting

Shear strength of unsaturated soil is an important engineering property in various geotechnical designs. In response to varying climatic conditions, unsaturated soil behaves differently under the drying and wetting processes due to hysteresis. Many research works were conducted and numerous equations were proposed for unsaturated shear strength, however, most of them were limited to the soil under the drying process. In this study, shear strength equations were categorized according to the nature of equation, i.e., fitting and prediction type equations. The purpose of this study is to propose prediction type shear strength equations for unsaturated soil under drying and wetting. Twelve published shear strength equations were selected for evaluation. A series of unsaturated consolidated drained triaxial tests were conducted on statically compacted sand-kaolin specimens under drying and wetting to examine the validity of the proposed equations. The experimental results indicated that the specimens on the drying path had a higher shear strength and exhibited more ductility, less stiffness, and contraction during shearing while the specimens on the wetting path had a lower shear strength and exhibited more brittleness, more stiffness, and dilation during shearing. The proposed equations were shown to provide the best predictions on the drying and wetting shear strength results from this study as well as published data in the comparison study.     

叠氏污泥脱水技术处理炼油厂“三泥”

分析了炼油厂“三泥”性质和脱水预处理对策,介绍了叠氏污泥脱水机特点原理及处理炼油企业“三泥”的典型应用实例.当处理罐底泥时,进料含水率在86.7％～90.2％时,经叠氏污泥脱水机脱水后泥饼含水率降为54.2％～55.9％;当处理剩余活性污泥时,进料含水率在95.5％～97.5％时,经叠氏污泥脱水机脱水后泥饼含水率降为78.0％～79.0％;当处理浮渣时,进料含水率在90.5％～92.0％时,经叠氏污泥脱水机脱水后泥饼含水率降为67.9％～68.7％.所处理物料的脱水泥饼的含水率均低于80％,满足污泥迸一步处理前的脱水需求,与离心机相比节电在1/10以上.     

Process analysis and optimisation of hybrid processes for the dehydration of ethanol

Promising hybrid processes for ethanol dewatering consist of different combinations of distillation with adsorption and/or vapour permeation. This paper presents an analysis and optimisation of these hybrid processes using non-equilibrium models and an evolutionary algorithm. Four different membrane assisted configurations are compared with a benchmark process consisting of distillation and pressure swing adsorption. In total 12 cases were investigated while assuming different feed and product compositions at different production capacities: three ethanol mass fractions in feed 45, 80, 92 wt.%, two product purities 99.6, 99.95 wt.% and two production capacities 25,000, 250,000 m³/year. The influence of decisive operating and structural variables on important target variables such as total membrane area is demonstrated. Finally, the processes are evaluated regarding operating costs and energy consumption depending on product purity and production capacity. The operating costs of the membrane assisted configurations differ only in a small range of −3% to 6% from those of the benchmark. The energy consumption of the membrane assisted configurations without distillation is up to 30% lower compared to the benchmark. Especially the combination of vapour permeation and adsorption is a promising alternative allowing for producing ethanol with high purities at lower operating pressures compared to the vapour permeation as stand alone process.     

Dewatering of Sewage Sludge

Dewatering of sewage sludges is usually carried out using belt filter presses or centrifuges. The ability to remove water from sludges by mechanical dewatering is a property of both the sludge and the equipment used for dewatering. Newer high-solids centrifuges can remove more water than a belt press but require a higher chemical conditioning dose. The Gt value, the product of the mean velocity gradient and the shear time, has been found to be a useful parameter for characterizing the shear in mechanical dewatering equipment. Dewatering can be considered a two-step process, filtration followed by expression. The expression step is the most important of these and the benefits of various sludge processing techniques and conditioning chemical types remains a fruitful area of research.