粉尘爆炸强度分级方法存在问题分析

介绍了目前国际上粉尘爆炸强度分级方法及分级判据，并对其存在的问题进行了分析，在此基础上提出新的等级划分及分级判据。     

利用磷霉素生产盐渣合成阻垢剂

将磷霉素生产盐渣经水解得到右旋磷霉素二钠,再通过亲核取代反应得到可用作循环冷却水阻垢剂的氨基二乙基(1-甲基-2-羟基)膦酸四钠(ADMHP·Na4),并用FTIR表征了产物结构.实验结果表明:在取代反应温度为25℃、取代反应时间为2h、n(氨水)∶n(右旋磷霉素二钠)=8的条件下,由右旋磷霉素二钠制备ADMHP·Na4,收率可达83.87％.处理1t盐渣可创造利润3 080元.当ADMHP·Na4质量浓度为30 mg/L,水样温度为60℃时,ADMHP·Na4对CaCO3的阻垢效果较好,阻垢率可达91.47％.     

TiO2-Bi2O3纳米粒子气相光催化降解对二甲苯

采用沉淀法制备了TiO2-Bi2O3纳米粒子,并对其进行结构表征.以制得的TiO2-Bi2O3为光催化剂,以对二甲苯为目标污染物,研究了对二甲苯气相光催化氧化降解的影响因素.实验结果表明:经750 ℃焙烧的光催化剂对对二甲苯的催化效果最好;随氧气加入量的增加,对二甲苯的降解率增大;少量水蒸气的加入,可增大对对二甲苯降解率;采用L-H动力学模型得到对二甲苯光催化降解的反应速率常数和吸附常数分别为0.089 5 μmol/(L· min)和0.000785 L/μmol.     

气升式环流生物反应器处理废水厌氧过程研究

采用气升式环流生物反应器处理模拟废水。周期性通入空气和氮气来实现厌氧一好氧交替过程。对厌氧一好氧过程和普通好氧过程进行了对比,研究了厌氧处理时间和曝气速率对生物除磷效果的影响。结果表明,厌氧过程可以显著地增强生物除磷效果,与普通好氧过程相比,在进水总磷质量浓度为10mg／L时,磷的去除率可以提高30％,而COD的去除基本不受影响;适当延长厌氧处理时间和适当增大厌氧过程曝气速率可以改善厌氧环境及活性污泥性能,提高磷的去除率。     

Field Testing and Computer Modeling of an Oxygen Combustion System at the EPA Mobile Incinerator

The LINDE® Oxygen Combustion System has been demonstrated successfully at the EPA Denney Farm site as part of the modified EPA mobile incinerator. This paper describes the field testing results and computer modeling of the LINDE system. The oxygen system enables the EPA unit to incinerate dioxin and PCB contaminated soil at a consistent rate of 4000 lb/h—200 percent of the original maximum capacity. The pure oxygen combustion system improved the thermal efficiency of the incinerator by over 60 percent and reduced the flue gas volume dramatically. Therefore, the dust carryover problem was mitigated. The destruction and removal efficiencies of hazardous wastes exceeded EPA requirements.

The design of the proprietary burner allows the use of up to 100 percent oxygen in place of air for incineration with improvements over conventional oxy-fuel burners. As a result, the temperature distributions in the rotary kiln are uniform and NO_x emissions are low.

The oxygen combustion system, controlled by a programmable controller, provided much better response and flexibility than conventional air based systems. The system generated a stable flame and responsed well to the transient conditions of the rotary kiln. Kiln puff occurrence was virtually eliminated in the operation of the mobile incinerator.

A computer model of the incinerator was developed and used for the process design of the LINDE system. The model predicted the test results reasonably well. This model can be a useful tool in the design and operation of rotary kiln incineration systems.     

Time domain reflectometry measured moisture content of sewage sludge compost across temperatures

Time domain reflectometry (TDR) is a prospective measurement technology for moisture content of sewage sludge composting material; however, a significant dependence upon temperature has been observed. The objective of this study was to assess the impacts of temperature upon moisture content measurement and determine if TDR could be used to monitor moisture content in sewage sludge compost across a range of temperatures. We also investigated the combined effects of temperature and conductivity on moisture content measurement. The results revealed that the moisture content of composting material could be determined by TDR using coated probes, even when the measured material had a moisture content of 0.581 cm³ cm^?3, temperature of 70 °C and conductivity of 4.32 mS cm^?1. TDR probes were calibrated as a function of dielectric properties that included temperature effects. When the bulk temperature varied from 20 °C to 70 °C, composting material with 0.10–0.70 cm³ cm^?3 moisture content could be measured by TDR using coated probes, and calibrations based on different temperatures minimized the errors.     

Effects of organic ligands on fractionation of rare earth elements (REEs) in hydroponic plants: an application to the determination of binding capacities by humic acid for modeling

Previous studies have revealed the fractionation processes of rare earth elements (REEs) in hydroponic plants, with a heavy REE (HREE, the elements from Gd to Lu) enrichment in leaves. In this study, effects on the HREE enrichment in soybean leaves with additions of carboxylic acids (acetate, malate, citrate, NTA, EDTA and DTPA) and two soil humic acids (HAs) were investigated. REE speciation in carboxylic acid and HA solutions was simulated using Visual MINTEQ and Model V, respectively. The results showed that the effects caused by carboxylic acids were strongly dependent on the differences between their binding strengths for light REEs (LREEs, the elements from La to Eu) and those for HREEs. A good correlation existed between these effects and the changes of free REE ions in solutions. This relationship was also observed for the HA treatments, provided that the intrinsic equilibrium constants of REEs for cation–proton exchange with HA (i.e., pK_MHA) in Model V were estimated using a free-energy relationship with the stability constants for REE complexation with lactic acid. It is suggested that this set of pK_MHA values is more suitable for use in Model V for the simulation of REE complexation with HA.     

Photocatalytic degradation of mixed gaseous carbonyl compounds at low level on adsorptive TiO2/SiO2 photocatalyst using a fluidized bed reactor

An adsorptive silica-supported titania photocatalyst TiO(2)/SiO(2) was prepared by using nanosized titania (anatase) immobilized on silica gel by the sol-gel technique with the titanium tetra isopropoxide as the main raw material and acetic acid as the acid catalyst. Meanwhile the structure and properties of the TiO(2)/SiO(2) photocatalyst were studied by means of many modern analysis techniques such as TEM, XRD, and BET. Gas-solid heterogeneous photocatalytic decomposition of four carbonyl compounds mixture at low concentration levels over ultraviolet irradiated TiO(2)/SiO(2) photocatalyst were carried out with high degradation efficiencies in a coaxial triple-cylinder-type fluidized bed photocatalytic reactor, which provided efficient continuous contact of ultraviolet photons, silica-supported titania photocatalyst, and gaseous reactants. Experimental results showed that the photocatalyst had a high adsorption performance and a good photocatalytic activity for four carbonyl compounds mixture. Some factors influencing the photocatalytic decomposition of the mixed carbonyl compounds, i.e. the gas flowrate, relative humidity, concentration of oxygen, and illumination time, were discussed in detail. It is found that the photocatalytic reaction rate of four carbonyl compounds decreased in this order: propionaldehyde, acetone, acetaldehyde and formaldehyde.