天津石化乙烯装置裂解气压缩机喘振线验证方案

裂解气压缩机U-GB201是乙烯装置核心设备,采用透平驱动,其防喘振控制原来在DCS中实现,由于DCS系统扫描和执行速度慢,加上控制算法简单,属单参数(最低流量算法)控制方式,因此控制精度低,控制裕度大,机组运行时离喘振区远,耗费大量能量。改造后的ITCC系统采用成熟的模块化控制技术实现了防喘振控制功能,可以最大程度利用蒸汽做功,降低能耗。文章介绍了裂解气压缩机喘振线验证方案原理、风险和相应预防措施进行分析,并作出可实际运作的实施方案。     

染色温度的自动控制

染液温度对染色质量关系很大,过去一直是根据染色工艺要求,用手工开启或关闭蒸汽和水阀门,由于蒸汽压力的变动很难控制,产品会出现色差、色花等问题。 上海第十三毛纺织厂工人和技术人员,在兄弟单位的协助下,经过反复试验,试制成功     

蒸汽压缩机(热泵)工艺应用

文章对多效蒸发、蒸汽喷射器—热泵蒸发、蒸汽压缩机—热泵蒸发以及多级闪蒸等几种蒸发方式进行简单比较;并重点介绍了蒸汽压缩机(热泵)工艺及特点,蒸汽压缩机的选择及设备情况,热泵技术的节能分析、工业应用业绩及前景等。     

响应面分析法优化洗梗水温合格率的应用研究

以洗梗水温的合格率为评价指标,通过单因素试验、运用响应面和绝对差值分析法,考察了液位计安装位置、液位计高低检测位置、补偿蒸汽阀门开启和关闭点对洗梗水温合格率的影响.结果表明:液位计的安装位置为34 cm,低位检测位置为28 cm,高位检测位置为38 cm时,洗梗水温合格率的最大预测值为94.996%.当水温47.5℃时,补偿蒸汽阀门开度为100%;随着水温的增加逐渐减少补偿蒸汽阀门开度,当水温52.5℃时,关闭补偿蒸汽阀门.经对液位检测程序和补偿蒸汽阀门开启和关闭程序优化,YSG-8AF型洗梗机PID控制程序实现了加水和增温的自动控制,洗梗水温合格率从79.85%提高到99.92%.     

防喘振控制在压缩机改造中的应用

随着工业科技的蓬勃发展,排气量大、运转周期长的离心式压缩机逐渐赢得市场信赖。但不可忽略的是,频发的喘振现象已经成为离心式压缩机在工业应用中的首要桎梏。文章将从阐述离心式压缩机防喘振控制系统的研究目的入手,结合离心式压缩机工作原理、喘振现象成因以及防喘振控制系统要素等研究基础,提出防喘振控制系统设计方案,旨在为离心式压缩机改良提供有益参考。     

离心压缩机喘振原因及预防措施

阐述了离心式压缩机喘振机理、产生原因、风险及判定,以及离心压缩机防止喘振发生的措施。     

压缩机控制及保护系统设计探讨

在石油化工行业发展中,压缩机的应用较为广泛,其中以离心压缩机(简称"压缩机")为典型代表,存在重量小、装置效率高、油气污染少、经济性能优等显著特点,一定程度上解决了工况操作失误问题。但在部分特定工况下,压缩机的喘振现象较突出,较易造成机器无法正常使用,急需做好压缩机防喘振控制,避免更严重的操作事故。基于此,本研究结合压缩机使用现状,着重分析喘振的现象及原理,并针对具体问题提出压缩机控制及保护系统的设计方案,以期促进喘振问题研究进程。     

离心压缩机喘振及防范措施

文章介绍离心压缩机发生喘振给生产带来不可估量的损失,离心压缩机喘振时的剧烈振动和刺耳的噪声,从离心压缩机的内部叶片结构来分析产生喘振原因是气流在叶轮非工作面上产生严重脱离引起的。根据压缩机特性曲线和管网特性曲线分析出产生喘振相关联的外部因素:过滤器、空分系统、空压机冷却器、电网波动和操作人员引起的喘振,分析原因制定相应的措施来预防喘振带来的危害,为安全生产提供了坚实的保障。     

关于供水管网中阀门使用问题的研讨

为了适应现阶段供水管网工作的要求,进行阀门整体使用体系的健全是必要的。进行阀门开启、关闭环节的控制,有效减少管段的工作问题状况。文章就供水管网阀门问题展开分析,通过对实地调研及实地考察模式的开展,进行阀门使用方案的优化。     

ITCC综合控制系统在压缩机组控制中的应用研究

介绍了ITCC控制系统的构成及原理,分析了ITCC系统的功能特点;通过分析压缩机喘振现象的成因,给出了压缩机防喘振控制算法数学模型;提出了ITCC防喘振功能设计。ITCC系统操作简易、组态灵活,控制功能强大,应用市场广阔。     

Textural Properties of Cold-set Gels Induced from Heat-denatured Whey Protein Isolates

A 9% whey protein (WP) isolate solution at pH 7.0 was heat-denatured at 80°C for 30 min. Size-exclusion HPLC showed that native WP formed soluble aggregates after heat-treatment. Additions of CaCl2 (10–40 mM), NaCl (50–400 mM) or glucono-delta-lactone (GDL, 0.4–2.0%, w/v) or hydrolysis by a protease from Bacillus licheniformis caused gelation of the denatured solution at 45°C. Textural parameters, hardness, adhesiveness, and cohesiveness of the gels so formed changed markedly with concentration of added salts or pH by added GDL. Maximum gel hardness occurred at 200 mM NaCl or pH 4.7. Increasing CaCl2 concentration continuously increased gel hardness. Generally, GDL-induced gels were harder than salt-induced gels, and much harder than the protease-induced gel.     

Occurrence of bisphenol-F-diglycidyl ether (BFDGE) in fish canned in oil

The levels of bisphenol-F-diglycidyl ether (BFDGE) were quantified as part of a European survey on the migration of residues of epoxy resins into oil from canned fish. The contents of BFDGE in cans, lids and fish collected from all 15 Member States of the European Union and Switzerland were analysed in 382 samples. Cans and lids were separately extracted with acetonitrile. The extraction from fish was carried out with hexane followed by re-extraction with acetonitrile. The analysis was performed by reverse phase HPL C with fluorescence detection. BFDGE could be detected in 12% of the fish, 24% of the cans and 18% of the lids. Only 3% of the fish contained BFDGE in concentrations considerably above 1mg/kg. In addition to the presented data, a comparison was made with the levels of BADGE (bisphenol-A-diglycidyl ether)analysed in the same products in the context of a previous study.     

Contribution of European research to risk analysis

The European Commission's, Quality of Life Research Programme, Key Action 1—Health, Food & Nutrition is mission-oriented and aims, amongst other things, at providing a healthy, safe and high-quality food supply leading to reinforced consumer confidence in the safety of European food. Its objectives also include the enhancing of the competitiveness of the European food supply. Key Action 1 is currently supporting a number of different types of European collaborative projects in the area of risk analysis. The objectives of these projects range from the development and validation of prevention strategies including the reduction of consumers risks; development and validation of new modelling approaches; harmonization of risk assessment principles, methodologies, and terminology; standardization of methods and systems used for the safety evaluation of transgenic food; providing of tools for the evaluation of human viral contamination of shellfish and quality control; new methodologies for assessing the potential of unintended effects of genetically modified (genetically modified) foods; development of a risk assessment model for Cryptosporidium parvum related to the food and water industries; to the development of a communication platform for genetically modified organism, producers, retailers, regulatory authorities and consumer groups to improve safety assessment procedures, risk management strategies and risk communication; development and validation of new methods for safety testing of transgenic food; evaluation of the safety and efficacy of iron supplementation in pregnant women; evaluation of the potential cancer-preventing activity of pro- and pre-biotic ('synbiotic') combinations in human volunteers. An overview of these projects is presented here.     

低温带皮菜籽粕微粉的不同粒级部分的功能特性

为研究低温带皮菜籽粕微粉的不同粒级部分的功能特性,以经低温脱脂的带皮菜籽粕为原料,经微粉碎后筛分成212~425μm、150~212μm和106~150μm的3个不同粒级的微粉样品,检测这些样品的吸水性、吸油性、乳化性和乳化稳定性、蛋白质体外消化率。结果表明:1 3个不同粒级的微粉样品之间的粗纤维含量存在显著差异,表明三者的结构组成成分有一定差异。23个微粉样品的乳化活性和乳化稳定性随粒度级别的减小而显著增加(P0.01)。33个微粉样品的蛋白质体外消化率随粒度级别的减小而显著增加(P0.01)。4不同粒级带皮菜籽粕微粉样品的吸水性与吸油性受其结构组成物质不同和粒度的双重影响,与粒度的相关性不明显。     

Microbiology of food taints

Fresh and processed foods are often spoilt by the presence of undesirable flavours and odours caused by microbial action. The aim of this paper is to review the current knowledge of microbiologically induced taints that occur in a wide range of foodstuffs, including meats, poultry, fish, crustaceans, milk, dairy products, fruits, vegetables, cereals and cereal products. Examples have been chosen where the compounds responsible for the taint have been identified and sufficient data obtained to demonstrate the involvement of microorganisms. However, in some cases the full identity of the causative organism may not have been elucidated. The types of microorganisms covered by this review include bacteria, fungi, yeasts, actinomycetes and cyanobacteria. Although cyanobacteria do not in general infect foods, their presence in aqueous systems and water supplies can lead to off-flavours in aquatic organisms and processed foodstuffs. Several examples of each of these processes are discussed. Wherever possible, the likely biosynthetic pathway used by the microorganism to produce the offending compound in a foodstuff is indicated.     

Analysis for organic residues from aids to polymerization used to make plastics intended for food contact

Polymers intended for food contact use have been analysed for organic residues which could be attributed to a range of substances employed as polymerization aids (e.g. initiators and catalysts). A wide range of polymers was extracted with solvents and the extracts analysed by gas chromatography-mass spectrometry (GC-MS). The overwhelming majority of substances identified were not derived from aids to polymerization but were oligomers, additives and adventitious contaminants. However, a small number of substances were identified as initiator residues. These included tetramethylsuccinonitrile (TMSN) which was observed in two polymers and it derived from recombination of two azobisisobutyronitrile (AIBN) initiator radicals. Methyl benzoate, benzoic acid, biphenyl and phenyl benzoate were detected in one poly(methyl methacrylate) sample and in two polyvinylchlorides and they are thought to be derived from benzoyl peroxide initiator. TMSN was subsequently targeted for analysis of poly-(methyl methacrylate) plastics using proton nuclear magnetic resonance spectrometry (¹     

Tests of potential functional barriers for laminated multilayer food packages. Part II: Medium molecular weight permeants

Experiments were performed to characterize the kinetics of the permeation of different medium molecular weight model permeants: bisphenol A, warfarin and anthracene, from liquid paraffin, through a surrogate potential functional barrier (25 microns-thick orientated polypropylene--OPP) into the food simulants olive oil and 3% (w/v) acetic acid. The characterization of permeation kinetics generally observed the permeation models previously reported to explain the experimental permeation results obtained for a low molecular weight group of model permeants. In general, the model permeants exhibited behaviour consistent with their relative molecular weights with respect to (a) the time taken to attain steady-state permeation into the food simulant in which they were more soluble, (b) their subsequent steady-state permeation rates, and (c) their partition between liquid paraffin and the OPP membrane.     

The development of reference materials for paralytic shellfish poisoning toxins in lyophilized mussel. I: Interlaboratory studies of methods of analysis

This paper describes the first part of a project undertaken to develop mussel reference materials for Paralytic Shellfish Poisoning (PSP) toxins. Two interlaboratory studies were undertaken to investigate the performance of the analytical methodology for several PSP toxins, in particular saxitoxin (STX) and decarbamoyl-saxitoxin (dc-STX) in lyophilized mussels, and to set criteria for the acceptance of results to be applied during the second part of the project: the certification exercise. In the first study, 18 laboratories were asked to measure STX and dc-STX in rehydrated lyophilized mussel material and to identify as many other PSP toxins as possible with a method of their choice. In the second interlaboratory study, 15 laboratories were additionally asked to determine quantitatively STX and dc-STX in rehydrated lyophilized mussel and in a saxitoxin-enriched mussel material. The first study revealed that three out of four postcolumn derivatization methods and one pre-column derivatization method sufficed in principle to determine STX and dc-STX. Most participants (13 of 18) obtained acceptable calibration curves and recoveries. Saxitoxin was hardly detected in the rehydrated lyophilized mussels and results obtained for dc-STX yielded a CV of 58% at a mass fraction of 1.86 mg/kg. Most participants (14 out of 18) identified gonyautoxin-5 (GTX-5) in a hydrolysed extract provided. The first study led to provisional criteria for linearity, recovery and separation. The second study revealed that 6 out of 15 laboratories were able to meet these criteria. Results obtained for dc-STX yielded a CV of 19% at a mass fraction of 3.49mg/kg. Results obtained for STX in the saxitoxin-enriched material yielded a CV of 19% at a mass fraction of 0.34mg/kg. Saxitoxin could not be detected in the PSP-positive material. Hydrolysis was useful to confirm the identity of GTX5 and provided indicative information about C1 and C2 toxins in the PSP-positive material. The methods used in the second interlaboratory study showed sufficiently consistent analysis results to undertake a certification exercise to assign certified values for STX and dc-STX in lyophilized mussel.     

The Ministry of Environmental Protection Issued "Feasible Technology Guidelines for Pollution Prevention and Control in Wood Pulping Process of the Paper Industry (Trial)" and Two Other Guiding Technical Documents

On December 27t＂, 2013, the Ministry of Environmenta Protection announced that, in order to implement ＂The Environmental Protection Law of the People＇ s Republic of China＂, improve the working system in environmenta protection technologies, and promote technologica advancement in pollution prevention, the Ministry of Environmental Protection sponsored the formulation of three guiding technical documents including ＂Feasible Technology Guidelines for Pollution Prevention and Contro n Wood Pulping Process of the Paper Industry （Trial）＂     

1~(st) Intelli-Tissue~ EcoEc Tissue Machine Supplied by PMP Group Successfully Put into Operation in China

正On April 29th,2014,Intelli-Tissue EcoEc tissue machine supplied by PMP Group successfully put into operation at Hebei Xuesong Paper Co.,Ltd.,this is the first such kind of paper machine of PMP Group in China.