Liquefaction of sawdust in hot compressed ethanol for the production of bio-oils

Direct liquefaction of lignocellulosic waste (sawdust) has been conducted in hot-compressed ethanol at temperatures from 150 to 250 °C. It was found that polyols such as glycerol, glycol and polyethylene glycol (PEG) promoted liquefaction process assisted with hot ethanol treatments seemed promising for production of bio-oils from lignocellulosic materials. Effects of different solvents and catalysts on liquefaction of sawdust were investigated. The results showed that the optimum operating condition for catalytic liquefaction is at 250 °C, 1 h of reaction time using glycerol and ethanol as solvent where operating at this condition realized the highest conversion of sawdust which is 97.8%. After reaction, the liquified product was separated by vacuum distillation. Two fractions were obtained, namely light oil and heavy oil. The properties and compositions of these two fractions were characterized in terms of Fourier transform infrared spectroscopy (FT-IR), gas chromatography–mass spectrometry (GC–MS), size exclusion chromatography (SEC) and nuclear magnetic resonance (NMR).     

Thermal hazard evaluation for γ-valerolactone production by using formic acid as hydrogen donor

Aiming at the green and sustainable energy substitution and supply, biomass valorization has become a potential strategy to face the energy crisis and increasing demand all over the world from long-term perspectives. Among the bio-based chemicals, γ-valerolactone (GVL) production from hydrogenation of levulinic acid (LA) and its esters has attracted great interests due to its wide applications, such as fuel, solvent, and additives. However, the safety evaluation for this hydrogenation reaction has received few attentions. To fill this gap, thermal hazard evaluation for GVL production from LA hydrogenation by using formic acid (FA) as hydrogen donor was first performed. The process conditions were optimized by using orthogonal experimental method for further calorimetry study. Thermal stability of chemicals and thermal risk of reaction process under adiabatic conditions were investigated by applying differential scanning calorimetry and accelerating rate calorimeter Phi-Tec II, respectively. The results revealed that the chemicals were stable in temperature range from 30 to 250 °C except FA due to its evaporation and decomposition with endothermic behaviors. The reaction process under isothermal and adiabatic conditions demonstrates that the decomposition of FA was rapid and followed by the hydrogenation of LA to GVL. Based on kinetic model under adiabatic conditions and risk matrix, the thermal runaway risk was found to be medium, indicating that certain safety measures should be properly designed and taken for loss prevention. This work could benefit the safety design and thermal risk prevention for GVL production by using FA as hydrogen donor.     

氨联产甲醇物料的危险性辨识、评价及安全措施

氨联产甲醇生产法是生产甲醇的一种主要方法。甲醇生产中的物料都是比较危险的化学品,该类化学品易燃、易爆,容易使人中毒,如果管理不善,一旦发生意外,将造成巨大经济损失和重大人员伤亡。笔者按照OHSMS(职业安全健康管理体系)标准,对氨联产甲醇生产系统中生产过程物料和成品物料的危险性进行辨识和评价,提出了在氨联产甲醇生产系统中有关生产运行的安全管理控制措施,为氨联产甲醇生产系统的安全生产提供了切实可行的手段和途径,旨在提醒人们对氨联产甲醇生产系统的安全生产引起充分重视。     

LPCVD法制备TiO_2纳米薄膜的生命周期评价

针对纳米材料生产的高能耗、低生产率的特点,用生命周期评价(LCA)方法对纳米TiO_2薄膜生产过程进行了环境影响评价,并通过设置不同的低压化学气相沉积过程(LPCVD)工艺参数,研究了工艺参数中温度和压强对于TiO_2薄膜评价结果的影响。研究显示,纳米TiO_2薄膜生产阶段的环境表现受LPCVD过程工艺参数影响,评价结果可用于指导LPCVD工艺优化。     

Process analysis of an industrial waste-to-energy plant: Theory and experiments

Thermal conversion is fundamental in an integrated waste management system due to the capability of reducing mass and volume of waste and recovering energy content from unrecyclable materials. Indeed, power generation from industrial solid wastes (ISW) is a topic of great interest for its appeal in the field of renewable energy production as well as for an increasing public concern related to its emissions. This paper is based on the process engineering and optimization analysis, commissioned to the University Campus-Biomedico of Rome by the MIDA Tecnologie Ambientali S.r.l. enterprise, ended up in the construction of an ISW thermo-conversion plant in Crotone (Southern Italy), where it is nowadays operating. The scientific approach to the process analysis is founded on a novel cascade numerical simulation of each plant section and it has been used initially in the process design step and after to simulate the performances of the industrial plant. In this paper, the plant process scheme is described together with the values of main operating parameters monitored during the experimental test runs. The thermodynamic and kinetic basics of the mathematical model for the simulation of the energy recovery and flue gas treatment sections are presented. Moreover, the simulation results, together with the implemented parameters, are given and compared to the experimental data for 10 specific plant test runs. It was found that the model is capable to predict the process performances in the energy production as well as in the gas treatment sections with high accuracy by knowing a set of measurable input variables. In the paper fundamental plant variables have been considered such as steam temperature, steam flow rate, power generated as well as temperature, flow rate and composition of the resulting flue gas; therefore, the mathematical model can be simply implemented as a reliable and efficient tool for management optimization of this kind of plants.     

酚类化合物对小白鼠脾脏细胞DNA毒性的构效相关研究

应用彗星实验技术,测定了12种酚类化合物对小白鼠脾脏细胞DNA的损伤水平.应用Hansch法和量子化学MOPAC-PM3方法计算了12种酚类化合物的辛醇-水分配系数、分子折射率、分子最高占据轨道能和分子中最正原子电荷.运用SPSS统计软件进行回归分析,对小白鼠脾脏细胞DNA的损伤率进行了定量结构-活性相关研究(QSAR).结果表明,酚类化合物的亲脂性参数和分子折射率能有效地表征它们所引起的DNA的损伤程度.由化合物的电性效应引起的细胞毒性可忽略.     

Occupational chemical exposure and risk estimation in process development and design

Each year more people die from diseases caused by work than are killed in industrial accidents. Therefore, methods are needed to evaluate occupational health hazards as early as possible when the process is still under development. A method for estimating inhalative exposures and risks in petrochemical and related plants is presented. The method is simple and suffices with the limited data availability during the early design stages.The steps of the method, which utilizes preliminary process flow diagrams are as follows: first the fugitive emissions and process plot areas are estimated based on precalculated process modules representing the typical process sections (such as a distillation unit). Chemical concentration in the air is then calculated based on the wind velocity probability and the estimated process cross-sectional area. For this purpose a typical wind velocity distribution in the area is used. The worker risk of exposure to chemicals is evaluated either based on the concentration in air by using the hazard quotient method or calculating the carcinogenic chemicals intake and the resulting risk of cancer. The values are compared to the benchmarks.As a result the process route health characteristics such as fugitive emissions rate, critical wind speed, chemical concentration in air and intake amount as well as the corresponding risk of exposure are produced. By using statistical meteorological data, health risks of occupational exposure can be estimated more realistically as probabilities. The approach is capable of comparing alternative processes to select the concept which is inherently occupationally healthier. Using this method, the exposure problems of a process can be identified earlier and proper decisions can be made early in process development or predesign stage.The concentration-based method is demonstrated by a case study of six competing manufacturing routes for methyl methacrylate (MMA). The C3 is found to be the most harmful alternative to health. Both concentration-based and intake-based methods are applied. The study indicates that the intake-based risk estimation benchmark is stricter than the exposure limit-based benchmark for carcinogens.     

二氧化碳与水预处理煤样对甲烷吸附热效应特性的实验研究

研究煤体吸附甲烷的热效应对于深入揭示煤层气在煤表面的吸附机理有重要意义。通过C80微量量热仪测试了无烟煤、焦煤、褐煤在二氧化碳与水预处理前后的甲烷吸附热力学参数,得到甲烷的等温吸附曲线和吸附热曲线,并建立了甲烷吸附量—吸附热定量模型,从能量角度解释了煤样预处理前后对甲烷的吸附特性。研究结果表明:经二氧化碳与水预处理后,煤样对甲烷的吸附量以及吸附过程产生的微量吸附热均有所增加,且预处理对煤体造成的影响主要体现在能增大其表面孔隙结构。     

面向危化品仓储堆垛三维几何重建的单目视觉标定算法研究

为了解决安全生产部门对危化品仓存储缺乏有效技术手段的问题,构建了五元组参数单目视觉成像模型并提出一种相机标定方法。该方法无需已知相机内参数信息,仅通过2个标识点成像关系就可实现参数标定,避免了传统算法实现过程复杂、运算量大等问题。标定得到的参数作为堆垛三维几何重建运算的基本条件,重建的效果则客观评价了标定参数的精确性。试验结果表明:提出的标定算法易于实现,其结果在堆垛几何重建过程中有较强的鲁棒性,重建结果与实际情况比较误差很小,适用于危化品仓储五距的监管。     

Nonlinear molecular based modeling of the flash point for application in inherently safer design

New chemical process design strategies utilizing computer-aided molecular design (CAMD) can provide significant improvements in process safety by designing chemicals with required target properties and the substitution of safer chemicals. An important aspect of this methodology concerns the prediction of properties given the molecular structure. This study utilizes one such emerging method for prediction of a hazardous property, flash point (FP), which is in the center of attention in safety studies. Using such a reliable data set comprising 1651 organic and inorganic chemicals, from 79 diverse material classes, and robust dynamic binary particle swarm optimization for the feature selection step resulted in the most efficient molecular features of the FP investigations. Apart from the simple yet precise five-parameter multivariate model, the FP nonlinear behavior was thoroughly investigated by a novel hybrid of particle swarm optimization and support vector regression. Besides, 195 missing experimental FPs of the DIPPR data set are predicted via the presented procedure.     

A multi-criteria approach to screening alternatives for converting sewage sludge to biodiesel

The search for cheaper feedstock for use in the production of biofuels such as biodiesel has turned attention to various forms of waste products including animal fats, waste oils and now lipids in sludge. With the potential of obtaining sludge at a reduced cost, free, or possibly with incentives, sewage sludge is being investigated as a potential feedstock for biofuel production. For the extraction of oils from the sewage sludge and the subsequent processing, there are various alternatives that should be designed, analyzed, and screened. In developing and screening these alternatives, it is necessary to have a consistent basis for comparing alternatives based on key criteria. While most of the design studies focus on techno-economic criteria, it is also important to include safety metrics in the multi-criteria analysis. In this work, a detailed economic analysis and a safety evaluation are performed on a process involving extraction of triglycerides and fatty acids, pre-treatment of fatty acids (direct conversion to biodiesel), and transesterification of triglycerides to biodiesel. Four solvents, toluene, hexane, methanol and ethanol, are individually used in the extraction process. The resulting triglycerides and fatty acids from each extraction are modeled in the pre-treatment process. ASPEN Plus software is used to simulate the detailed process. Economic analysis is performed using ASPEN ICARUS, and scale-up of a previously analyzed process is used to estimate the cost of the biodiesel portion of the process. A new safety metric (referred to as the Safety Index “SI”) is introduced to enable comparison of the various solvent extraction processes. The SI is based on solvent criteria as well as process conditions. A case study is presented to demonstrate the insights and usefulness of the developed approach. The results of the techno-economic analysis reveal that of the four solvents used for the initial extraction, hexane and toluene were least costly (2.89 and 2.79 $/gal, respectively). Conversely, the safety analysis utilizing the SI reveals that methanol and ethanol are the safer solvent options. The issue of cost/safety tradeoffs is also discussed.     

高等学校危险化学品安全管理探讨

危险化学品是高等学校各学科领域在教学、科研过程中广泛使用的实验用品.因其具有易燃、易爆、易中毒、腐蚀性等特点,容易发生安全事故,是高等学校实验室安全管理工作的一个重要内容.结合我校危险化学品的一些管理措施,从四方面论述了高等学校如何切实做好危险化学品的安全管理工作.     

On the gasification of biomass: Data analysis and regressions

The use of solid wastes as a way to produce energy and chemicals is one of the frontiers in chemistry. One of these methods is the biomass gasification. In this thermal treatment the biomass is heated in a partially oxidising environment using different process conditions.The variability of both biomass composition and process conditions can lead the thermal treatment to several different results. In order to find a methodology for the classification of all the involved data a dataset containing biomass characterization, gasification process conditions and obtained syngas properties have been gathered from the literature.This dataset has been analysed through multivariate analysis. Principal component analysis (PCA) and a partial least square analysis (PLS) have been performed. Several correlations among different biomass and their gasification products have been found among input parameters, such as biomass properties and process conditions, and output variables like products composition and properties.     

Engineering for Sustainable Development (ESD) in Bio-Diesel Production

Engineering for sustainable development (ESD) is an integrated systems approach, which aims at developing a balance between the requirements of the current stakeholders without compromising the ability of the future generations to meet their needs. This is a multi-criteria decision-making process that involves the identification of the most optimal sustainable process, which satisfies economic, ecological, social criteria as well as safety and health requirements. Certain difficulties are encountered when ESD is applied such as ill-defined criteria, scarcity of information, lack of process-specific data, metrics and the need to satisfy multiple decision makers. To overcome these difficulties ESD can be broken down into three major steps, starting with the life cycle assessment (LCA) of the process, followed by generation of non-dominating alternatives, and finally selecting the most sustainable process by employing an analytic hierarchical selection process. This methodology starts with the prioritization of the sustainability metrics (health and safety, economic, ecological and social components). Then the alternatives are subjected to a pair-wise comparison with respect to each Sustainable Development (SD) indicator and prioritized depending on their performance. The SD indicator priority score and each individual alternative's performance score together are used to determine the most sustainable alternative. In this paper, the analysis approach and metrics for ESD are applied to bio-diesel production.     

微生物吸附处理低浓度含铀废水的效能

生物吸附是目前处理低浓度含铀废水最有前途的方法之一.本文探讨了不同种类微生物的来源及其对铀的吸附效能.分析了生物吸附过程的影响因素和吸附机理.细菌、放线菌、真菌和藻类对铀的吸附能力依次递减,pH值、菌种预处理、共存离子和金属初始浓度是生物吸附的主要影响因素;微生物的细胞结构在生物吸附过程中发挥了重要的作用,静电吸附、酶促反应、无机微沉淀和氧化还原等是生物吸附的主要机理.最后预测了生物吸附处理低浓度含铀废水的研究方向.     

Effluent stream treatment in a nitrogenous fertilizer factory: An exergy analysis for process integration

The industrial processes used for the production of nitrogenous fertilizers are the main generators of reactive nitrogen compounds, chemicals and effluents that ultimately impact the biosphere. Exergy analysis has been performed to a nitrogen fertilizer factory in the State of Bahia, Brazil, where the Anaerobic Ammonium Oxidation (Anammox) and other physical–chemical processes are used to partially or totally handle the feed streams normally sent to a stripping tower.The results showed that the combined use of physical–chemical and biological process can improve the overall exergetic efficiency and avoid the emission of reactive compounds to the atmosphere allowing the recovery of the condensate lost as effluent, so that it can be reincorporated in the production of steam network, increasing energy efficiency and environmental performance of the process.     

基于FUZZY-AHP的危化品管道运输 安全等级综合评判模型与应用

为有效控制与降低危化品管道运输风险,以国家安全生产法和危化品输送管道安全管理规定为基础依据,与我国危化品管道运输现状相结合,建立以危化品管道运输安全等级为目标层的评价指标体系后,基于层次分析法(AHP)理论与模糊数学综合评价法(FUZZY),构建其综合评价模型。通过实例验证表明,该模型对危化品管道运输安全等级的确立科学且有效,所得结论对于提升危化品管道运输安全等级有较好的理论和实践指导作用。     

Applications of dust explosion hazard and disaster prevention technology

Powdered materials are widely used in industrial processes, chemical processing, and nanoscience. Because most flammable powders and chemicals are not pure substances, their flammability and self-heating characteristics cannot be accurately identified using safety data sheets. Therefore, site staff can easily underestimate the risks they pose. Flammable dust accidents are frequent and force industrial process managers to pay attention to the characteristics of flammable powders and create inherently safer designs.This study verified that although the flammable powders used by petrochemical plants have been tested, some powders have different minimum ignition energies (MIEs) before and after drying, whereas some of the powders are released of flammable gases. These hazard characteristics are usually neglected, leading to the neglect of preventive parameters for fires and explosions, such as dust particle size specified by NFPA-654, MIE, the minimum ignition temperature of the dust cloud, the minimum ignition temperature of the dust layer, and limiting oxygen concentration. Unless these parameters are fully integrated into process hazard analysis and process safety management, the risks cannot be fully identified, and the reliability of process hazard analysis cannot be improved to facilitate the development of appropriate countermeasures. Preventing the underestimation of process risk severity due to the fire and explosion parameters of unknown flammable dusts and overestimation of existing safety measures is crucial for effective accident prevention.     

刨花板及其木质原材料燃烧热解特性对比试验

为研究刨花板与木质原材料热解燃烧过程的区别,利用热重分析仪对空气和氮气条件下刨花板及其木质原材料进行研究。深入分析材料的燃烧热解失重过程的热重法和微商热重法曲线特性,确定了材料的燃烧特征参数。材料的燃烧热解动力学过程符合"双阶段一级反应"模型,利用考斯特-瑞地芬(Coats-Redfern)方法求得对应失重阶段的动力学参数。通过对比发现,刨花板较其木质原材料着火温度低,燃尽温度高,综合燃烧特性指数低;燃烧热解活化能和频率因子低,高温段失重率高;燃烧最终剩余质量和其木质原材料基本相同,热解剩余质量大于木质原材料。根据试验现象对刨花板燃烧热解过程中胶黏剂的作用机理进行了推断。     

Wet bench reactive hazards of cleaning stages in semiconductor manufacturing processes

According to the research from FM Global (Factory Mutual Insurance Company), most of the incidents that have occurred in semiconductor plants in the past two decades were reported as “Fire Cases”. They claim that the fires in wet chemical cleaning processes were mainly caused by heater failure. However, depending on the process conditions, electrical heaters are designed to turn off automatically when the temperature reaches a set point. Therefore, a thorough study of the situations related to possible fires in wet chemical cleaning processes is necessary.

This study focused on the incompatible behaviors of cleaning materials used in the wet bench stage. These results can be applied to determine the causes of fires in the wet bench stage from using reactive chemicals for cleaning purposes.

Another purpose of this study was to investigate the potential hazards of widely used chemicals (hydrogen peroxide, concentrated sulfuric acid, hydrochloric acid and isopropyl alcohol) within similar processes in semiconductor plants. Experimental data were also verified in order to establish a concentration triangular diagram, which could be used to identify a combustion, deflagration or even detonation zone. Finally, this study can provide basic design data for an inherently safer process to avoid potential hazards caused by dangerous mixtures, which may result in large property loss in semiconductor plants.