变频调速在恒压供水系统的应用

本文以达拉特发电厂水场工业供水系统变频改造为例,介绍了一种替代压力水罐供水的基于PLC和变频调速器的恒压供水系统的结构和工作原理。该系统采用变频调速方式自动完成泵组软启动并自动调节水泵电机转速,使水压平稳过渡。通过PLC控制系统实现自动加、减水泵,并采用"先启先停"的控制方式实现水泵无冲击切换。当变频器故障或系统断电时,系统可切换至手动运行方式,保证不间断供水。采用软、硬件备用和钟控方式,使各水泵进行轮休,延长了设备的使用寿命。     

珠轮水泵自控节电

广州珠江轮胎有限公司的生产供水系统是从巴江河边取水源，通过一级泵将河水抽到过滤池，经处理后流进蓄水池；再通过二级泵，将水抽到千米之外的山顶水池，以供生产之用。为保证山顶水池有较高水位，蓄水池就必须有足够的水供二级泵使用。过去一级泵总是满载运行，蓄水池用不完的水则从溢流孔溢流。造成电能的极大浪费。为了使供水系统既能安全运行又能节约能耗，我们设计了一套用变频调速装置来控制水泵电机转速的系统：通过对蓄水池液位测量的信号自动反馈给调节器，由调节器送出控制信号给变频调速装置，变频器给出信号拖动水泵电机。电…     

浅谈凝结水泵工频改变频利弊

为了节能,凝结水泵新增变频器,运行方式由原来的工频运行转为变频运行,由通过除氧器上水调门调节控制除氧器水位转为主要通过调节凝结水泵转速来控制。变频器的应用虽然能节约不少电能,但也存在很多问题。岱海电厂#2机凝结水泵由工频转为变频运行时,发生过两次故障,本文着重从故障曲线和凝结水泵变频启动曲线上分析原因及凝结水泵变频运行时的性能情况,以及凝结水泵在工频运行和变频运行时的差异。     

供水泵站变频与工频水泵的优化配置

水泵运行电费占供水系统运行管理费用的很大比例,因此研究降低水泵能耗具有重要意义。从供水泵站节能运行出发,提出了水泵优化配置的节能方式,选用恒压变频供水方式。首先修正了常用供水管网水力分析软件(EPANET)中变频泵效率计算方法,通过调用供水管网水力分析软件核心计算函数及遗传算法,模拟实际供水中保持泵站出口压力恒定的运行工况。基于该模拟方法,模拟计算了5种水泵搭配方案,在不同设计流量下计算泵站全天的耗电量,对比总结了不同方案之间的优缺点。结果表明,通过丁频与变频水泵的合理搭配,节能效果较好。     

轮胎硫化动力供水系统的改造

采用智能软启动器、交流变频调速器和ＰＬＣ等主要部件对硫化车间的动力供水系统进行了自动化改造。改造后的供水系统中,供水泵由原来的４台（供一次水和二次水各２台）减少到２台（取消了一次水供水泵）、而且供水系统对硫化机台的供水压力更加稳定,还大大节约了电能。     

甲醇酸脱洗涤塔三段液位调节

我公司甲醇装置酸脱洗涤塔(C15201)三段出口阻力大,制约了装置产能的发挥。技改方案是增加输送泵(P15212),采用三段液位变频控制。对三段升压泵的恒转速方案、全流量变频调节方、优选流量范围的变频调节进行了对比分析,总结了工艺负荷通过离心泵变频控制的注意事项。     

循环冷却水系统的复合节电方式实践

以并联水泵供水的循环冷却水系统为节电对象,分步实施了水泵叶轮切削,单台水泵变频调速的组合控制方案,优化了水泵的工作点,实现了自动调节的恒压供水,完全消除了泵后闸阀的节流损失,总体节电率达46.8%。     

除氧水供水调速运行综合效益分析

为了解决轮胎硫化水压力波动大、泵压高、耗电高等诸多问题,决定将除氧水供水系统改用变频调速。文中通过理论推导得出结论:采用变频调速后节约的功率等于阀门节流功率和泵的损失功率之和。且压力波动范围控制在±0.04MPa之内,原来常年开两台泵,现在只需开一台就可满足生产需求。采用变频控制后经济效益显著。     

变频调速恒压供水系统

邢矿集团金牛钾碱分公司（以下简称钾碱）的生产上水两台和消防上水泵1台,系统采用变频调速方式自动调节水泵电机转速或加、减泵。这样可以自动完成泵组软启动及无冲击切换,使水压平稳过渡。尤其是变频器故障时,系统仍可运行,保证不间断供水,系统断电恢复后可自启动。采用硬件/软件备用及钟控功能,使各泵进行轮休,延长了设备的机械使用寿命。     

变频—节能降耗的一种方法

变频是目前风机、水泵节能的一种较好方案,通过现场参数的测量和计算,可以大概计算出节电率;把循环水泵的出口阀门完全打开,采用PID调节,通过变频器改变电压的频率,从而改变循环水电动机的转速,让电动机不需要克服阀门的阻力而消耗电能,以致达到变频节能的目标。     

Many Drugs of Abuse May Be Acutely Transformed to Dopamine,Norepinephrine and Epinephrine In Vivo

It is well established that a wide range of drugs of abuse acutely boost the signaling of the sympathetic nervous system and the hypothalamic–pituitary–adrenal (HPA) axis, where norepinephrine and epinephrine are major output molecules. This stimulatory effect is accompanied by such symptoms as elevated heart rate and blood pressure, more rapid breathing, increased body temperature and sweating, and pupillary dilation, as well as the intoxicating or euphoric subjective properties of the drug. While many drugs of abuse are thought to achieve their intoxicating effects by modulating the monoaminergic neurotransmitter systems (i.e., serotonin, norepinephrine, dopamine) by binding to these receptors or otherwise affecting their synaptic signaling, this paper puts forth the hypothesis that many of these drugs are actually acutely converted to catecholamines (dopamine, norepinephrine, epinephrine) in vivo, in addition to transformation to their known metabolites. In this manner, a range of stimulants, opioids, and psychedelics (as well as alcohol) may partially achieve their intoxicating properties, as well as side effects, due to this putative transformation to catecholamines. If this hypothesis is correct, it would alter our understanding of the basic biosynthetic pathways for generating these important signaling molecules, while also modifying our view of the neural substrates underlying substance abuse and dependence, including psychological stress-induced relapse. Importantly, there is a direct way to test the overarching hypothesis: administer (either centrally or peripherally) stable isotope versions of these drugs to model organisms such as rodents (or even to humans) and then use liquid chromatography-mass spectrometry to determine if the labeled drug is converted to labeled catecholamines in brain, blood plasma, or urine samples.     

Direct observation of freeze-thaw instability of latex coatings via high pressure freezing and cryogenic SEM

Despite its industrial importance, the subject of freeze-thaw (F/T) stability of latex coatings has not been studied extensively. There is also a lack of fundamental understanding about the process and the mechanisms through which a coating becomes destabilized. High pressure (2100 bar) freezing fixes the state of water-suspended particles of polymer binder and inorganic pigments without the growth of ice crystals during freezing that produce artifacts in direct imaging scanning electron microscopy (SEM) of fracture surfaces of frozen coatings. We show that by incorporating copolymerizable functional monomers, it is possible to achieve F/T stability in polymer latexes and in low-VOC paints, as judged by the microstructures revealed by the cryogenic SEM technique. Particle coalescence as well as pigment segregation in F/T unstable systems are visualized. In order to achieve F/T stability in paints, latex particles must not flocculate and should provide protection to inorganic pigment and extender particles. Because of the unique capabilities of the cryogenic SEM, we are able to separate the effects of freezing and thawing, and study the influence of the rate of freezing and thawing on F/T stability. Destabilization can be caused by either freezing or thawing. A slow freezing process is more detrimental to F/T stability than a fast freezing process; the latter actually preserves suspension stability during freezing. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, October 27–29, 2004 in Chicago, IL. Tied for first place in The John A. Gordon Best Paper Competition.     

Ethanol and (−)-α-Pinene: Attractant Kairomones for Bark and Ambrosia Beetles in the Southeastern US

In 2002–2004, we examined the flight responses of 49 species of native and exotic bark and ambrosia beetles (Coleoptera: Scolytidae and Platypodidae) to traps baited with ethanol and/or (−)-α-pinene in the southeastern US. Eight field trials were conducted in mature pine stands in Alabama, Florida, Georgia, North Carolina, and South Carolina. Funnel traps baited with ethanol lures (release rate, about 0.6 g/day at 25–28°C) were attractive to ten species of ambrosia beetles (Ambrosiodmus tachygraphus, Anisandrus sayi, Dryoxylon onoharaensum, Monarthrum mali, Xyleborinus saxesenii, Xyleborus affinis, Xyleborus ferrugineus, Xylosandrus compactus, Xylosandrus crassiusculus, and Xylosandrus germanus) and two species of bark beetles (Cryptocarenus heveae and Hypothenemus sp.). Traps baited with (−)-α-pinene lures (release rate, 2–6 g/day at 25–28°C) were attractive to five bark beetle species (Dendroctonus terebrans, Hylastes porculus, Hylastes salebrosus, Hylastes tenuis, and Ips grandicollis) and one platypodid ambrosia beetle species (Myoplatypus flavicornis). Ethanol enhanced responses of some species (Xyleborus pubescens, H. porculus, H. salebrosus, H. tenuis, and Pityophthorus cariniceps) to traps baited with (−)-α-pinene in some locations. (−)-α-Pinene interrupted the response of some ambrosia beetle species to traps baited with ethanol, but only the response of D. onoharaensum was interrupted consistently at most locations. Of 23 species of ambrosia beetles captured in our field trials, nine were exotic and accounted for 70–97% of total catches of ambrosia beetles. Our results provide support for the continued use of separate traps baited with ethanol alone and ethanol with (−)-α-pinene to detect and monitor common bark and ambrosia beetles from the southeastern region of the US.     

Insect antifeedant properties of anthranoids from the genusVismia

Vismiones and ferruginins, representatives of a new class of lypophilic anthranoids from the genusVismia were found to inhibit feeding in larvae of species ofSpodoptera, Heliothis, and inLocusta migratoria.     

ICP-MS法测定地球化学样品中As、Cr、Ge、V等18种微量痕量元素的研究

建立了测定地球化学样品中包括As、Cr、Ge、V等18种微量、痕量元素的ICP-MS方法。地化试样用HF-HNO3混酸分解后,以1 1 HNO3溶解干渣。由于制样不使用盐酸,避免了Cl对As、Cr、Ge、V的质谱干扰。用国家一级地球化学标准物质GBW 07309制备溶液优化仪器工作参数,并用于校准。方法测定限(6s)为:0.007~6.4μg/g,精密度(RSD%,n=12)为:29%~9.4%,经过国家一级地球化学标准物质的分析验证,结果与标准值吻合。方法已应用于国土资源调查的试样分析。     

Novel polyurethane coating technology through glycidyl carbamate chemistry

Glycidyl carbamate chemistry combines the excellent properties of polyurethanes with the crosslinking chemistry of epoxy resins. Glycidyl carbamate functional oligomers were synthesized by the reaction of polyfunctional isocyanate oligomers and glycidol. The oligomers were formulated into coatings with several amine functional crosslinkers at varying stoichiometric ratios and cured at different temperatures. Properties such as solvent resistance, hardness, and impact resistance were dependent on the composition and cure conditions. Most coatings had an excellent combination of properties. Studies were carried out to determine the kinetics of the curing reaction of the glycidyl carbamate functional oligomers with multifunctional and model amines. Detailed kinetic analysis of the curing reactions was also undertaken. The results indicated that the glycidyl carbamate functional group is more reactive than a glycidyl ether group. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, on October 27–29, 2004, in Chicago, IL.     

Highly moisture-proof polysilsesquioxane coating prepared via facile sol-gel process

A highly moisture-proof polysilsesquioxane coating was obtained from a new bis-silylated precursor, which was synthesized from 3-aminopropyltriethoxysilane (APTES) and m-xylylene diisocyanate (m-XDI) in tetrahydrofuran (THF) and verified by ¹H MAS NMR. For direct comparison purposes, an SiO₂ coating was also prepared by the Stöber method using tetraethoxysilane (TEOS) as the reactant. Interestingly, the coating obtained from the polysilsesquioxane sol exhibited a much higher moisture resistance capability than its counterpart, which was attributed to its more compact feature between nanoparticles as characterized by N₂ absorption experiment and transmission electron microscopy (TEM). Furthermore, its high transparency of about 92% showed potential for application in the protection of optical crystals.