某污水处理厂提标改造工程存在的问题及对策分析

某城镇生活污水处理厂提标改造工程由于设计过程中很多细节考虑不够仔细,导致该工程存在较多影响后续正常运行的问题。本文分析该污水处理厂提标改造项目采用的处理工艺特点及在调试运行过程中遇到的问题,提出应对措施,保证提标工程的正常运行。     

陕北地区某污水厂提标改造工程MBR膜设计及调试运行分析

随着我国水污染问题日益突显,城镇污水处理排放标准的提高已是大势所趋。近年来,各地污水处理厂的提标改造工作正在陆续进行。该污水处理厂提标改造工程设计出水水质为《陕西省黄河流域污水综合排放标准》(DB61/224-2018)中的A标准,据2020年1～3月的调试运行数据分析,MBR平板膜运行稳定。介绍工程设计情况及工艺特点,并总结设计和运行经验。     

云南某污水处理厂氧化沟工艺提标扩建

云南某污水处理厂提标扩建工程,对一期改良氧化沟工艺进行改造,二期扩建采用改良氧化沟+二沉池+高效沉淀池+滤布滤池+消毒工艺,提标扩建后出水水质由《城镇污水处理厂污染物排放标准》(GB1 891 8-2002)的一级B标准稳定提升至一级A标;为同类污水处理厂的提标及扩建设计提供参考.     

印制电路板污水处理厂提标改造措施探索

印制电路板废水成分复杂、形态不一,处理难度较大,本文以某印制电路板污水处理厂的提标改造为案例,介绍了印制电路板废水种类,对废水处理及回用提出建议,以期通过对这一典型案例,为同类污水处理厂的提标改造提供参考.     

UCT大型污水处理厂提标改造工艺方案探讨

某大型污水处理厂一期工程现有生化处理工艺为UCT工艺,设计规模20万m3/d,出水水质执行《城镇污水处理厂污染物排放标准》(GB18918-2002)一级B标准。应要求,提标后出水水质标准应执行《地表水环境质量标准》(GB3838-2002)中的准Ⅳ标准。本文对多种提标改造工艺进行比对分析,为类似工程提供技术参考。     

城镇污水处理厂提标改造技术路径分析与探讨

城镇污水处理厂是预防生活污水大范围污染自然水体的主要途径,我国早期建设的城镇污水厂尾水排放标准已不能满足现今日益严峻的水环境状况.为此,城镇污水厂提标改造势在必行.本文列举了两个提标改造案例,并从几个主要的污水排放指标提升入手,就提标改造技术路线进行了分析探讨.     

活性砂技术在污水深度处理中的应用探讨

根据现在城镇污水处理厂提标改造的背景和要求,对现有工艺进行综合分析和比较.结果表明活性砂滤池具有明显的优势,值得推广应用.     

污水处理设施提标对城市雨源型河流旱季水质达标的影响

针对污水处理厂提标问题,以我国南方某典型雨源型河流为例,通过实测分析计算河流旱季主要污染源对主要污染物的贡献权重,并进一步通过河流水质模拟预测分析了污水处理厂提标对河流关键断面水质达标的影响,探讨了污水处理厂进一步提标的经济合理性。结果表明,沿岸污水处理设施是河流污染物的主要来源,污染源COD、TN、NH_3-N、TP分别占96.5%、99.0%、97.6%、97.0%;将出水标准低于一级B的临时应急型污水处理设施出水标准提高到一级A时,河流COD、NH_3-N分别提升22.1%、72.2%,一级B提标为一级A或一级A提标为地表水V类标准对河流水质提升效果不明显;污水处理厂需进一步提升TP、TN的出水标准,特别是TN的出水标准,才能满足远期河流断面水质达到地表水Ⅲ类标准的目标,但应综合考虑提标的优先次序和进一步提标的必要性。     

关于城镇污水处理厂提标改造的探讨

在城市化进程不断深入的背景下,城镇污水量显著提升,同时,国家对污水处理厂排放指标又提出了更为严格的要求,这无疑给城镇污水处理工作带来较大的挑战。在节能环保的理念下,必须对城镇污水进行妥善处理和并及时对污水厂开展技术改造,使其满足日益严格的污水排放指标。针对城镇污水处理厂提标改造进行了详尽地分析,旨在为今后的工作提供一定借鉴价值。     

供热燃气锅炉低氮改造的分析

上海市提出2018年至2020年底前全面完成中小燃油、燃气锅炉提标改造工作。根据此要求和公司2019年实施的提标低氮改造项目实施情况,结合上海市及全国其他省市已公开的数据进行了分析,针对适用性更广、运行更可靠的低氮燃烧器与烟气外循环相结合的改造方式,从选型、施工、调试、运行的角度提出了一些建议。     

The structure of diffusion flames burning pure,binary, and ternary solutions of methanol,heptane, and toluene

The structure of counterflow diffusions flames burning heptane, toluene, binary solutions of methanol and toluene, and heptane and toluene, and ternary solutions of methanol, heptane, and toluene is characterized in the vicinity of extinction. Composition profiles of stable species were measured in these flames by use of gas sampling with quartz microprobes and analyzed by use of on-line, two column gas chromatography. Temperature profiles were measured by use of coated thermocouples. A number of compounds were observed during pyrolysis of the fuel. Experimental results were analyzed by using the mixture fraction (conserved scalar) as the independent variable. Results show that for a diffusion flame burning heptane the approximation that the Lewis numbers for all species are approximately equal to unity is valid. When the composition profiles for major chemical species and temperature profiles are plotted with mixture fraction as the independent variable, the maximum value of the concentration of the major stable species and the maximum value of the temperature were found to occur on the rich side of stoichiometry. For diffusion flames burning solutions of methanol, heptane, and toluene, the compositions of the hydrocarbon fuels were observed to extrapolate to a value of zero at nearly the same location; however, methanol was observed to extrapolate to a value of zero at a different location. It is suggested that a previously developed theoretical analysis which did not allow the fuel concentrations to attain a value of zero at different locations may give slightly inaccurate results, when used to predict flame extinction.     

Components,formulations, solutions,evaluation, and application of comprehensive combustion models

Development and application of comprehensive, multidimensional, computational combustion models are increasing at a significant pace across the world. While once confined to specialized research computer codes, these combustion models are becoming more readily accessible as features in commercially available computational fluid dynamics (CFD) computer codes. Simulations made with such computer codes offer great potential for use in analyzing, designing, retrofitting, and optimizing the performance of fossil-fuel combustion and conversion systems.The purpose of this paper is to provide an overview of comprehensive combustion modeling technology as applied to fossil-fuel combustion processes. This overview is divided into three main parts. First, a brief review of the state-of-the-art of the various components or submodels that are required in a comprehensive combustion model is presented. These submodels embody mathematical and numerical representations of the fundamental principles that characterize the physico-chemical phenomena of interest. The submodel review is limited to those required for characterizing non-premixed, gaseous and pulverized coal gasification and combustion processes. A summary of the submodels that are available in representative computer codes is also presented.Second, the kinds of data required to evaluate and validate the predictions of comprehensive combustion codes are considered. To be viewed with confidence, code simulations must have been rigorously evaluated and validated by comparison with appropriate experimental data, preferably from a variety of combustor geometries at various geometric scales. Three sets of validation data are discussed in detail. Two sets are from the highly instrumented, pilot-scale combustor called the controlled profile reactor (CPR) (one natural gas-fired and one coal-fired), and the other set is for a full-scale, corner-fired 85 MW_e utility boiler.Third, representative applications of comprehensive combustion models are summarized, and three sets of model simulations are compared with experimental data. The model simulations for the three test cases were made using two commonly used, CFD-based computer codes with comprehensive combustion model features, PCGC-3 and FLUENT 4.4. In addition to the standard version of FLUENT, predictions were also made with a version of FLUENT incorporating advanced submodels for coal reactions and NO pollutant formation.     

Research,development and the prospect of combined cooling,heating, and power systems

The development of a combined cooling, heating, and power (CCHP) system in China is presented in this paper. The key scientific problems of a distributed energy system and the integration principles of a CCHP system are also pointed out. Moreover, two corresponding CCHP systems: one with the complementarities of fossil fuels energy and renewable energy, and the other integrated with desalination technology, are investigated. With special attention to thermal energy utilization, the integrating characteristics of these systems are likewise revealed, and the important role that the principle of cascade utilization of physical energy plays in system integration is identified. We have found that the energy-saving ratio of the integrated CCHP systems can be as high as 30%, and as such, the innovative CCHP systems suitable for China's sustainable development are also recommended.     

The production of fuel from,and the thermal stability of,sunflower oil,corn oil,and canola oil

Frying of sunflower, corn, and canola oils was carried out for seven running days at 175°C in this study. Fatty acid composition, free fatty acid, viscosity, iodine value, peroxide value, density, pH, saponification value, refractive index, average molecular weight, color, and the higher heating value of these oils have been analyzed. While the contents of free fatty acid, viscosity, saponification value, peroxide value, and colors (red and yellow) increase with the frying times, the contents of average molecular weight, iodine value, pH, and the higher heating value decreased for all oils in this work. However, reduction in the higher heating value is relatively low. This work indicated that recycling as a fuel of these oils can make a major economic contribution.     

Solar optical properties of thin films of Cu, Ag, Au, Cr, Fe, Co, Ni and Al

The optical properties of metal coated glass substrates have been investigated. Thin films of various thicknessesof the noble metals: Cu, Ag, Au, the transition metals: Cr, Fe, Co, Ni and the free electron-like metal Al were thermally evaporated onto glass substrates. The front and backside reflectance and the transmittance between 0.35 and 15 μm were measured. The obtained data were used to calculate the integrated values of solar reflection and transmission as a function of metal film thickness. The application of metal films on domestic windows as sun-screens and heat-mirrors are discussed. It is concluded that Cu is the best coating in a window system if good heat insulating properties are desired. This is due to its ability to remain continuous at very thin film thicknesses. An infra-red reflectance of 86 per cent combined with a solar transmittance of 55 per cent was obtained for a 70film. For solar heat-protection Au-films are found to be superior owing to their transmittance peak in the middle of the visible wavelength region. The transition metals are less selective than the noble metals, but due to their flat response-curves in the visible range they cause a smaller change in colour of the transmitted and reflected light.     

Providing all global energy with wind,water, and solar power,Part I: Technologies,energy resources,quantities and areas of infrastructure,and materials

Climate change, pollution, and energy insecurity are among the greatest problems of our time. Addressing them requires major changes in our energy infrastructure. Here, we analyze the feasibility of providing worldwide energy for all purposes (electric power, transportation, heating/cooling, etc.) from wind, water, and sunlight (WWS). In Part I, we discuss WWS energy system characteristics, current and future energy demand, availability of WWS resources, numbers of WWS devices, and area and material requirements. In Part II, we address variability, economics, and policy of WWS energy. We estimate that ∼3,800,000 5 MW wind turbines, ∼49,000 300 MW concentrated solar plants, ∼40,000 300 MW solar PV power plants, ∼1.7 billion 3 kW rooftop PV systems, ∼5350 100 MW geothermal power plants, ∼270 new 1300 MW hydroelectric power plants, ∼720,000 0.75 MW wave devices, and ∼490,000 1 MW tidal turbines can power a 2030 WWS world that uses electricity and electrolytic hydrogen for all purposes. Such a WWS infrastructure reduces world power demand by 30% and requires only ∼0.41% and ∼0.59% more of the world's land for footprint and spacing, respectively. We suggest producing all new energy with WWS by 2030 and replacing the pre-existing energy by 2050. Barriers to the plan are primarily social and political, not technological or economic. The energy cost in a WWS world should be similar to that today.     

Thermoenvironomic evaluation of simple,intercooled, STIG,and ISTIG cycles

Low‐technology cycle modifications available for improving gas turbine performance are still largely unexploited. Among those proven modifications, steam injection is found to be the most effective in boosting both the output capacity and thermal efficiency while reducing NO_x emissions. It further improves part load performance under varying ambient conditions. Intercooling is another low‐technology modification which can improve performance of simple and steam injected gas turbine cycles. Because of the uncertainties relating to an efficiency comparison of steam injected and simple cycle designs, the decision as to whether it is worthwhile to give more emphasis to steam injected cycles should be made on grounds other than efficiency alone. Therefore, this study comparatively evaluates simple, intercooled, steam injected (STIG), and intercooled steam injected (ISTIG) gas turbine cycles from the points of efficiency, network output, economics, and pollutant emissions using an advanced validated thermoenvironomic model. Optimum cycle parameters are investigated. Economic feasibility of steam injection and intercooling on simple and intercooled cycles are evaluated using an updated plant cost data. Total and environmental costs as well as profit of the plant owner are estimated for varying fuel costs and varying cycle parameters such as pressure, steam injection, and equivalence ratio. Results of our analysis based on the characteristic cycle parameters show that network output increases up to 22.2% and 14% respectively, when steam injection is implemented on simple and intercooled gas turbine cycles which correspond to up to 6.7% and 4.4% decrease in specific fuel consumption. Steam injection decreases NO_x emissions of simple and intercooled cycles up to 67.2% and 65.2% respectively, and provides up to approximately 126.3% increase in net profit of intercooled cycle at the expense of an increase in total cost by 3.3%.     

Grinding energy and physical properties of chopped and hammer-milled barley,wheat, oat,and canola straws

In the present study, specific energy for grinding and physical properties of wheat, canola, oat and barley straw grinds were investigated. The initial moisture content of the straw was about 0.13–0.15 (fraction total mass basis). Particle size reduction experiments were conducted in two stages: (1) a chopper without a screen, and (2) a hammer mill using three screen sizes (19.05, 25.4, and 31.75 mm). The lowest grinding energy (1.96 and 2.91 kWh t⁻¹) was recorded for canola straw using a chopper and hammer mill with 19.05-mm screen size, whereas the highest (3.15 and 8.05 kWh t⁻¹) was recorded for barley and oat straws. The physical properties (geometric mean particle diameter, bulk, tapped and particle density, and porosity) of the chopped and hammer-milled wheat, barley, canola, and oat straw grinds measured were in the range of 0.98–4.22 mm, 36–80 kg m⁻³, 49–119 kg m⁻³, 600–1220 kg m⁻³, and 0.9–0.96, respectively. The average mean particle diameter was highest for the chopped wheat straw (4.22-mm) and lowest for the canola grind (0.98-mm). The canola grinds produced using the hammer mill (19.05-mm screen size) had the highest bulk and tapped density of about 80 and 119 kg m⁻³; whereas, the wheat and oat grinds had the lowest of about 58 and 88–90 kg m⁻³. The results indicate that the bulk and tapped densities are inversely proportional to the particle size of the grinds. The flow properties of the grinds calculated are better for chopped straws compared to hammer milled using smaller screen size (19.05 mm).     

Conveyance,envy, and homeowner choice of appliances

Conveyance, i.e. the fact that an appliance purchased will be left in a dwelling when moving out, may lead homeowners to purchase appliances of lower quality or performance, because the extra costs are not entirely capitalized into the house sales price. Employing a discrete choice experiment with homeowners in the United States, this paper explores the effects of conveyance on homeowners' willingness-to-pay for various attributes of refrigerators. To account for the social nature of purchases when conveyance is likely to occur, it also tests the role of envy (elicited through an incentivized game). The findings provide evidence that conveyors are more likely than non-conveyors to purchase a smaller refrigerator, from a less well-known brand, and with lower customer ratings. In contrast, conveyance was not found to affect homeowners' choices when it comes to energy cost. In addition, envy was found to generally reinforce the negative effects of conveyance on homeowners' willingness-to-pay for several quality and performance attributes. While conveyance and its interaction with envy help explain why some homeowners choose certain quality/performance attributes of appliances, these factors do not appear to explain the energy efficiency paradox.