EDI系统调试关键因素分析

通过EDI系统实际工程调试和数据分析,探讨了UF＋二级RO＋EDI系统作为锅炉补给水的可靠性,试验结果发现出水压差及预处理CO2去除率是决定EDI系统稳定运行的关键因素。     

水中余氯在线监测系统

本文介绍应用流动注射分析技术的一种快速、准确、灵敏和简便的余氯在线监测方法。分析频率120次/小时,检测限0.02mg/l,测定0.9mg/l余氯的相对标准差(R.S.D.)为1.2％,测定范围0—15mg/l。水中共存离子及环境温度对测定的影响不显著。对现场连续监测中的连续采样装置、过滤装置、试剂消耗及注射阀的磨损泄漏等方面的问题进行了探讨。采用PC—1500微处理机及其接口,实现数据采集及处理。     

螺旋式电除盐器—不用酸碱再生的去离子设备

离子交换技术的应用历史悠久 ,离子交换器已成为工业水处理中不可缺少的设备。然而 ,离子交换器运行一定时间后 ,必须用大量酸碱对树脂进行再生。所以 ,使用这种设备酸碱费用较高 ,劳动强度较大 ,对排放的废水必须处理 ,设备和下水道必须防腐。长期以来 ,人们不断研究不用酸碱和无公害的再生离子交换树脂的方法 ,国外最近开发成功的电去离子法 ( EDI) ,是一种将电渗析技术和离子交换技术结合在一起的脱盐新工艺。由于它能够连续不断地去除水中的离子 ,因此又称为连续去离子法( CDI)。1　EDI的应用和 DCJ的问世图 1　 DCJ纵截面结构示…     

石灰石-石膏湿法烟气脱硫装置的防腐蚀

主要介绍了华能珞璜电厂 4× 36 0MW机组石灰石 -石膏湿法烟气脱硫装置的内衬防腐技术及防腐蚀效果。通过对装置的运行考核 ,分析鳞片树脂衬里防腐蚀的对症性和可靠性     

我国水中余氯测定标准的对比分析

分析了国内水中余氯测定标准的现状,从标准适用范围、标准对象、方法原理、样品预处理、干扰物和方法的精密度等方面对现行标准进行了分析讨论,提出目前国内水中余氯测定标准存在现状复杂、技术内容重复、术语名称和定义不统一、样品预处理、保藏和运输规定与检测方法之间不协调、方法的质量指标不同等问题,并对今后余氯测定标准化工作提出建议,特别是针对标准对象名称混乱和技术内容重复等现象,对标准制/修订工作提出了及时复审或修订标准、对关键技术内容开展比对试验以探讨差异存在必要性等建议。     

电厂锅炉补给水系统中反渗透装置清洗的探讨

通过对锅炉补给水处理系统中反渗透装置的多次化学清洗,结合水质条件和运行实际情况,提出反渗透膜清洗药品选型和反渗透膜清洗措施,并对反渗透装置运行及清洗存在的问题进行了总结,为同类清洗反渗透装置在运行效果、清洗效果以及延长膜运行寿命方面提供参考。     

中国石油化工集团公司烟气脱硫装置的现状分析及建议

对中国石油化工集团公司已经投入运行的部分动力站烟气脱硫装置进行了现场调研,通过调研了解了企业脱硫设施的建设状况和运行状况,总结了取得的成绩,分析了存在的主要问题,为确保今后烟气脱硫装置长周期、稳定、经济运行,提出了严格生产运行管理和加强技术开发等一系列的建议,并对今后烟气脱硝提出了设想。     

大港油田苦咸再生水反渗透工艺自动控制研究

分析了大港油田污水回用深度处理工程苦咸再生水反渗透工艺仪表配置及自动控制方式,介绍了苦咸再生水反渗透系统亟待解决的各类问题。着重论述了仪表设置、余氯控制、结垢污堵控制、微生物污堵控制的实际运行方式,探讨了苦咸再生水反渗透工艺的技术可行性和可靠性。     

广东省火电厂烟气脱硫装置运行情况分析

对广东省11个火电厂脱硫装置的运行情况进行了调研和分析,总结了脱硫装置运行中普遍存在的问题,并提出了相应的建议,对于脱硫装置的运行优化具有参考意义。     

湿法脱硫吸收塔在线监测系统常见问题及解决办法

在线监测装置是运行人员的＂眼睛＂,能否正常运行,对整套脱硫系统的可靠、经济、甚至安全运行均有十分重要的影响。脱硫系统所属的关键在线监测装置包括压降测量装置、吸收塔浆液密度和液位测量装置、吸收塔浆液pH值测量装置,堵塞是三者所存在的共性问题,后两者还存在其他方面的常见问题,分析了某厂湿法脱硫吸收塔在线监测系统产生上述常见问题的原因,提出了相应的解决办法。     

电渗析技术及其应用

电渗析技术是膜分离技术之一,具有低能耗,高效率,连续运行、环境友好等显著优点,在多个行业中有着广泛的使用。简述了几种常见的电渗析技术,包括填充床电渗析,倒极电渗析和双膜电渗析等,着重介绍了电渗析技术在水处理、食品和化工方面的应用,并简单探讨了电渗析技术其发展前景。     

钯负载泡沫镍电极电化学还原水中三氯乙酸

采用非电沉积法制备了钯负载泡沫镍电极,运用SEM技术对其进行了表征,并以其阴极、铂丝为阳极进行了电化学还原三氯乙酸的研究,考察了工艺条件对三氯乙酸降解效果的影响,并对反应动力学和反应机理和进行了探讨。结果表明:钯负载泡沫镍电极具有较高的比表面积和良好的储氢性能;以20 mmol/L硫酸钠为电解质,在电解温度为20℃、钯负载量为4.5 mg/cm~2的条件下恒流(10 mA)电解240 min,三氯乙酸降解率达99.76%,氯原子脱除率达73.86%;三氯乙酸的电化学还原反应过程以及三氯乙酸上未脱除氯原子浓度的变化均符合拟一级反应动力学方程;三氯乙酸在电化学还原过程中逐个脱除氯原子。     

Pyrolysis kinetics of waste PVC pipe.

The pyrolysis kinetics of waste PVC pipe was investigated with a thermal gravimetric analysis system at heating rates of 5, 10, and 30 degrees C/min in a nitrogen atmosphere. Freeman-Carroll method was employed to evaluate kinetic parameters. Two dominant peaks were observed on derivative gravimetric curves, hypothetically suggesting a two-stage apparent reaction model. The first-stage reaction was likely to be represented by stoichiometric reaction to yield volatiles (mainly HCl) and intermediates. The second-stage reaction might be described by thermal degradation of intermediates competitively into gas, liquid, and solid by-products. Quasi-isothermal operations were introduced to verify the reaction types of the first and second reaction. The generation reaction of intermediates achieved at lower temperatures was carried out independently with their decomposition reaction at higher temperatures. The effects of additives on the pyrolysis kinetics of waste PVC pipe seem to be significant, especially on the first-stage reaction. The first-stage reaction was retarded. A merged peak at low temperatures was observed on the derivative thermogravimetry (DTG) curve instead of two peaks usually observed for that of pure PVC resin. The first peak on the DTG curve of pure PVC resin may shift more, resulting in the complete overlap of two peaks. The quantity of evolved HCl was likely to decrease because of interaction of metal components of stabilizers with either HCl or active chlorine atom or both. The final residual fraction increased as a result of pyrolysis of organic forms of additives to yield extra char. On the other hand, the second-stage reaction kinetics demonstrates a similar pattern to that of pure PVC resin, implying that the effects of additives may be less significant in comparison with that at the first-stage reaction.     

Water-soluble characteristics of chlorine in char derived from municipal solid wastes

Chlorine in char derived from municipal solid waste (MSW) was characterized and quantified based on its water solubility: easily water-soluble, hardly water-soluble, and non-water-soluble chlorine. For that, a four-cycle process of water-washing, heating or carbonation were carried out. In order to confirm the characteristics of non-water-soluble chlorine, additional thermal treatment and an alkali-acid washing process were applied to washed char. It was found that a large particle size of char (0.5-1.0 mm) significantly contributed to the amount of non-water-soluble chlorine. Pulverization and HNO3-HF digestion were performed to identify a factor to interfere chlorine release from char with a large particle size. Pulverization was proven ineffective for release of non-water-soluble chlorine, whereas approximately 32% of non-water-soluble chlorine was extracted by HNO3-HF digestion. Therefore, the presence of non-water-soluble chlorine is likely to originate from its chemical property rather than simply from its physical one.     

Study on chlorine removal from mixture of waste plastics

The recycling of waste plastics that include plastics that contain chlorine, such as polyvinyl chloride, is difficult because the chlorine leads to the corrosion of equipment. Then, the dechlorination method of waste plastics containing chlorine (CCWP) that consists of a series of melt process and hot water process was examined. CCWP was put into the melt process with coal tar (HOB) and converter dust (CD) to inhibit the diffusion of the chlorine-containing gas. The results indicated that iron oxide of the principal element of CD combines with chlorine eliminated from CCWP, and forms water-soluble iron chloride on the melt process. HOB dissolves or adsorbs a part of the chlorine during the melt process, and inhibits the diffusion of the chlorine-containing gas. Approximately 98% of the chlorine in the CCWP reacts with CD and forms iron chloride, which can be extracted on the hot water process.     

Recycling of carbon fiber-reinforced plastic using supercritical and subcritical fluids

The recycling of waste plastics is important for the prevention of the exhaustion of fossil resources. In this paper, recycling techniques of carbon fiber-reinforced plastic (CFRP) using supercritical and subcritical fluids were reviewed. The matrix resin of CFRP such as epoxy resin or resol resin was decomposed by supercritical and subcritical fluids, and the carbon fiber without thermal damage was recovered from CFRP. Mainly, water or alcohol was used as decomposition medium.     

Material flow analysis of RDF-production processes

The authors evaluate the possibilities of modifying the chemical characteristics of refuse-derived fuels (RDF) that are processed from residual household waste by mechanical operations to achieve and assure quality targets for relevant chemical concentrations, especially for heavy metals and chlorine. Quality assurance in the production of RDF demands that, together with an enrichment of the calorific value, highly toxic waste components are selectively separated and concentrated in a small stream to produce high yields of a relatively low polluted fuel. Based on the method of material flow analysis, a process evaluation is developed that considers the aspect of minimizing hazardous chemicals along with classical process data such as yield and product quality. Data on specific concentration of hazardous chemicals in waste components and their distribution in residual household waste as well as the results from large-scale test runs using different separation techniques demonstrate that mechanical operations alone are insufficient for separating hazardous chemicals. In the test runs, chemical compounds such as chlorine, cadmium and lead were often concentrated in the product. Even using optimized techniques, the ability to reduce hazards in the product is limited due to the distribution of the element concentration in the various components of the waste stream.     

Reactions of model compounds of phenol resin in sub- and supercritical water under an argon atmosphere

Model compounds of phenol resin were reacted in sub- and supercritical water to clarify the mechanism of the decomposition reaction of plastics in water. Cleavage reaction of methylene bonds was confirmed in the reactions of model compounds of phenol resin such as bis(hydroxyphenyl)methanes in sub- and supercritical water under an Ar atmosphere, although the methylene bond was stable in thermal reactions. It was also confirmed that sub- and supercritical water played important roles not only as a stable solvent thermally, but also as a chemical reagent. Received: July 19, 2000 / Accepted: September 14, 2000