尿素解析废液深度水解处理

本文介绍了云南天然气化工厂从意大利斯纳姆普罗吉蒂公司引进的尿素解析废液水解装置的设计基础数据、工艺流程、运行与考核评价等情况。尿素解析废液经水解装置处理后,氨的去除率可达99.99%,每年能从21.6万吨解析废液中回收氨约150吨,尿素2200吨,既增产了尿素,又减少氨氮对环境的污染;净化水可回用于系统,经精制处理后,亦可作锅炉给水,从而实现尿素解析废液不外排、闭路循环使用的目的。     

燃煤电站SCR烟气脱硝还原剂尿素热解热源的选择

介绍了燃煤电站SCR尿素热解工艺,结合当前燃料价格,通过工程案例计算,对比了各种尿素热解热源的运行费用。计算结果表明,高温蒸汽加热方案的运行费用最省,但在实际应用中受到相关条件的限制;在一定条件下,燃气加热与电加热方案是工程的优选技术方案。     

尿素为还原剂燃煤烟气脱硝技术的研究与应用

尿素由于运输、储存安全性较高，作为还原剂进行脱硝备受关注。从工艺原理、系统组成和工程应用等方面，对尿素制氨选择性催化还原技术（SCR）、选择性非催化还原技术（SNCR）和尿素法三种脱硝方法进行了综述。分析了不同技术运用过程存在的问题，并提出解决措施。     

含铜废催化剂中铜的回收

采用热解—氨浸工艺处理含铜废催化剂（w（Cu）为23.6%），优化了工艺条件，并通过蒸氨还原法制备出Cu₂O产品。实验结果表明：热解工段中，控制管式热解炉的空气流量为3.0 m³/min，在升温速率20 ℃/min、热解终温600 ℃、终温保持时间90 min的优化条件下，含铜废催化剂中的有机物热解完全;氨浸工段中，以NH₄Cl-NH₃-H₂O溶液为氨浸液，控制氨浸温度为40 ℃，在烧成料研磨时间90 min（粒径29.43 μm）、氨浸液总氨浓度4 mol/L、氨浸时间80 min的优化条件下，铜浸出率达到98%;经蒸氨还原法制得的Cu₂O产品的质量符合HG/T 2961—2010《工业氧化亚铜》中的一等品标准，产率为24%。     

尿素回收项目在山西焦化投入运行

2001年6月,山西焦化(集团)有限公司环保项目--尿素回收装置投入运行,为环保家族增添"新丁". 在尿素生产的蒸发工序中,部分尿素会在解析过程落入废液槽中,不仅使废液中的氨氮含量超标,而且使一部分尿素白白流失.尿素回收项目的实施可使尿素回收率达到85%,企业每年可回收尿素500多吨,增加收入45万元.     

化肥厂放空噪声治理技术总结

我厂是国内第一套渣油制氨生产尿素的大型化肥厂,年产合成氨30万t、尿素52万t。装置在开、停车时放空噪声高达132dB(A)。针对现状,我们组织人员研究制订了全厂放空噪声综合治理的技措方案,经过实施,取得了较为满意的效果。1 用安装消声器来治理化肥厂放空噪声化肥厂五大机组蒸气放空和各工艺系统放空时,大量10MPa和3.8MPa蒸汽及9.8     

烟气脱硝装置与电厂设备运行的相互影响

火电厂烟气脱硝装置中的二氧化硫、灰分、氨及催化剂中的各种重金属在高温烟气的作用下发生各种化学作用,生成的硫酸氢氨等产物对火电厂的各种设备均会产生不同影响.同时由于系统阻力及荷载的变化,也会对电厂其他相关设备产生影响,根据目前工程的运行经验,火电厂在增设脱硝装置后,均会对空气预热器、引风机、锅炉钢架等进行改造.通过综合分析烟气脱硝装置产生的影响原因及解决办法,为脱硝装置的设计提供参考.     

湿式镁法烟气脱硫副产物MgSO4热解回收MgO

通过对MgSO4的热解研究为湿式镁法烟气脱硫副产物的综合利用探索适宜的热解条件.实验结果表明,在升温速率为20 ℃/min、热解温度为850℃、恒温时间为2.0 h的条件下,由无水MgSO4热解制得的MgO收率高达99.8％.由MgSO4·7H2O热解制得的MgO收率仅为72.1％.由此表明,干燥的MgSO4对热解更有利.     

石化工业废硫酸的净化处理及回收利用

本文介绍了国外近年来对石化工业生产中产生的废硫酸采用稀释和中和、燃烧、水解与再浓缩、热解、萃取、氧化、盐析及冷冻结晶等方法净化处理,并加以回收,以及利用废硫酸直接制化工产品的新动向。     

废印制线路板真空热解产物分析

在自行设计的间歇式固定床真空热解装置中热解废印制线路板(PCB),对热解产物进行了分析.在热解温度为550 ℃、热解压力为20 kPa、恒温时间为60 min的条件下,得到的热解产物质量分数为:热解渣70%;热解油3%～4%;不可冷凝热解气26%～27%.经气相色谱-质谱联用(GC-MS)分析,热解油经常压蒸馏后得到的低沸点液态油中含有29种化合物,主要有苯酚、对异丙基酚、3-乙基酚、4-甲酚及2-溴苯酚,还含有少量含溴化合物和含氯化合物.热解油经简单的蒸馏就可达到回收酚类化合物的目的.热解渣经风选可实现铜与黏附有碳黑的玻璃纤维的分离,其中铜质量分数约30%,黏附有碳黑的玻璃纤维质量分数约70%.     

Paper fibers as a carbon source for the de novo formation of polychlorinated dioxins and furans

The formation of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDDs/Fs) from carbon that was produced by the pyrolysis of paper fibers and from wood charcoal was investigated experimentally. Fibers obtained from filter paper were pyrolyzed at 300° and 800°C to produce low- and high-temperature carbon samples. The two types of carbon and wood charcoal were mixed with silica (SiO₂) and trace copper oxide to produce three synthetic fly ash samples. Experiments to measure the formation of PCCDs/Fs from the three ash samples were conducted using a bench-scale reactor. The two carbon samples derived from paper fibers generated more PCDDs/Fs than was generated by the wood charcoal. The PCDDs/Fs generated by the low-temperature carbon and by the wood charcoal were dominated by the lower-chlorinated PCDFs. Such unique homologue distribution patterns are very similar to those generated by the open burning of household waste. The high-temperature carbon generated more highly chlorinated PCDDs/Fs. The effect of pyrolysis temperature on the de novo formation of PCDDs/Fs from residual carbon is discussed. Paper and paper products contained in household waste are likely to be the source of unburned carbon that contributes to high PCDD/F emissions in the open burning of household waste.     

Pyrolysis characteristics of bean dregs and in situ visualization of pyrolysis transformation

Biomass is an important renewable and sustainable source of energy. Waste products from biomass are considered as attractive feedstocks for the production of fuel. This work deals with the pyrolysis of bean dregs, a biomass waste from soybean processing industry. A technique has been developed to study bean dregs pyrolysis by in situ visualization of bean dregs transformation in a quartz capillary under a microscope using a charge-coupled device (CCD) camera monitoring system. The technique enables us to observe directly the processes and temperatures of bean dregs transformation during pyrolysis. In situ visualization of reaction revealed that how oily liquids are generated and expulsed concurrently from bean dregs during pyrolysis. Pyrolysis characteristics were investigated under a highly purified N₂ atmosphere using a thermogravimetric analyzer from room temperature to 800 °C at different heating rates of 10, 30 and 50 °C/min. The results showed that three stages appeared in this thermal degradation process. The initial decomposition temperature and the peak shifted towards higher temperature with an increase in heating rate. Kinetic parameters in terms of apparent activation energy and pre-exponential factor were determined.     

TG-DSC and FTIR study on pyrolysis of irradiation cross-linked polyethylene

Irradiation cross-linked polyethylene (PEX) and irradiation cross-linked polyethylene with carbon black filler (CB-PEX) are two types of scraps, generated in electric cable production. Their pyrolysis is studied in this work using instrumental TG\DSC\FTIR techniques and kinetic analysis. The experiments are performed at a constant heating rate of 10 °C/min in nitrogen flow at atmospheric pressure. It is found that the main pyrolysis stage is in the temperature range of 395–503 °C for PEX, and in range of 408–515 °C for CB-PEX. In the main pyrolysis stage, CB-PEX requires more external heat than PEX does. Olefins are the major products of pyrolysis for both materials, but they are quite different in their composition and molecular weight distribution. PEX can be converted almost quantitatively into volatile compounds. CB-PEX has a stronger coking tendency, as well as a larger residue composed of carbon black.     

Characteristics of healthcare wastes

A comprehensive understanding of the quantities and characteristics of the material that needs to be managed is one of the most basic steps in the development of a plan for solid waste management. In this case, the material under consideration is the solid waste generated in healthcare facilities, also known as healthcare waste. Unfortunately, limited reliable information is available in the open literature on the quantities and characteristics of the various types of wastes that are generated in healthcare facilities. Thus, sound management of these wastes, particularly in developing countries, often is problematic. This article provides information on the quantities and properties of healthcare wastes in various types of facilities located in developing countries, as well as in some industrialized countries. Most of the information has been obtained from the open literature, although some information has been collected by the authors and from reports available to the authors. Only data collected within approximately the last 15 years and using prescribed methodologies are presented. The range of hospital waste generation (both infectious and mixed solid waste fractions) varies from 0.016 to 3.23kg/bed-day. The relatively wide variation is due to the fact that some of the facilities surveyed in Ulaanbaatar include out-patient services and district health clinics; these facilities essentially provide very basic services and thus the quantities of waste generated are relatively small. On the other hand, the reported amount of infectious (clinical, yellow bag) waste varied from 0.01 to 0.65kg/bed-day. The characteristics of the components of healthcare wastes, such as the bulk density and the calorific value, have substantial variability. This literature review and the associated attempt at a comparative analysis point to the need for worldwide consensus on the terms and characteristics that describe wastes from healthcare facilities. Such a consensus would greatly facilitate comparative analyses among different facilities, studies and countries.     

尿素水溶液吸收SO2的机理研究

通过对尿素水溶液吸收SO2能力的机理研究发现，尿素水溶液在常温下（〈60℃）对SO2的吸收主要是物理吸收，而化学吸收受到尿素水解速率的控制，达到平衡后，其吸收效率在20％左右。     

淬火油泥的热解动力学分析及协同作用研究

采用热重差热分析法和傅里叶变换红外光谱分析联用的方法（TG-FTIR）研究淬火油泥（QOS）的热解过程,解析了热解过程的动力学特性,分析了其中的矿物油（MO）和残渣（SR）在QOS热解过程中的相互作用。实验结果表明：QOS热解过程包含油分热解阶段和矿物质分解阶段;低温段热解温度为150~520 ℃,高温段热解温度为800~980 ℃;SR的热解过程分为油分热解反应和残渣中Fe₂O₃的还原反应;MO的热解过程只有轻质油分的挥发和重质油分的热解。FTIR表征结果显示：QOS热解过程析出的气体主要为CO₂、CO和有机化合物;SR热解过程中CO₂的特征峰强度高于其他气体的特征峰强度;MO热解过程中烷烃的特征峰强度高于其他气体的特征峰强度,且MO主要以轻质油分为主。在QOS的热解过程中,初温~480 ℃时,SR所含的Fe₂O₃对MO的热解起促进作用,300 ℃左右时促进效果最明显。     

Characteristics of products and PCDD/DF emissions from a pyrolysis process of urethane/styrofoam waste from electrical home appliances

A plastic fraction consisting mainly of polyurethane/styrofoam waste is generated after separating valuable spare parts and metals from used electrical home appliances. In Korea, such waste is currently incinerated in cement kilns or is landfilled. However, owing to its high volatile matter content, conversion into gaseous or liquid pyrolysis products is a preferable alternative. A pyrolysis process of polyurethane and styrofoam waste from electrical home appliances was evaluated by characterizing the products generated at 500°–800°C. The para meters determined were the yields of gas, oil, and char; the characteristics of the remaining char; and the con centration of polychlorinated dibenzo-p-dioxins/polychlorinated dibenzo-furans in the product gas. As expected, the char yield decreased at higher temperatures, whereas gas and oil yields showed increasing tendency. The oil products could be used as storable fuels with a calorific value of 6000–8000 kcal/kg. Fine pores were observed in the char. The adsorption and decolorizing ability of the char were almost the same as those of activated carbon, so that pyrolysis char has potential for use as a sorbent. Further feasibility studies will be needed before utilizing pyrolysis technology to recover either fuels or usable products from polyurethane/styrofoam waste.