Pressure pulsations in piping system excited by a centrifugal turbomachinery taking the damping characteristics into consideration

Pressure pulsations excited by a centrifugal turbomachinery such as compressor, fan or pump at the blade passing frequency may cause severe noise and vibrations in piping system. Therefore, the practical evaluation method of pressure pulsations is strongly recommended. In particular, the maximum pressure amplitude under the resonant conditions should be appropriately evaluated. In this study, a one-dimensional excitation source model for a compressor or pump is introduced based on the equation of motion, so as to incorporate the non-linear damping proportional to velocity squared in the total piping system including the compressor or pump. The damping characteristics of the compressor or pump are investigated by using the semi-empirical model. It is shown that the resistance coefficient of the compressor or pump depends on the Reynolds number that is defined using the equivalent velocity of the pulsating flow. The frequency response of the pressure amplitude and the pressure distribution in the piping system can be evaluated by introducing the equivalent resistance of the compressor or pump and that of piping system. In particular, the relation of the maximum pressure amplitude in piping system to the location of the excitation source under resonant conditions can be evaluated. Finally, the reduction of the pressure pulsations by use of an orifice plate is discussed in terms of the pulsation energy loss.     

Alcohol‐Processable Organic Amorphous Electrolytes as an Effective Electron‐Injection Layer for Organic Light‐Emitting Diodes

A new series of monoammonium‐based organic electrolytes with the tetrafluoroborate (BF₄^?) counteranion have been synthesized. Replacing the pendant ethyl groups in the fluorenyl unit with 4‐ethoxyphenyl groups dramatically improves both solubility and morphological stability. The characterization of the alcohol‐processable amorphous ionic compounds as an electron‐injection layer in organic light‐emitting diodes (OLEDs) reveals that the organic electrolyte that comprises a rigid linear‐conjugated unit provides better device performance, with respect to its counterpart containing a branched bulky moiety. The capability of these compounds to facilitate electron injection from air‐stable aluminum metal is preliminarily discussed on the basis of the investigations of the electron‐only devices and photovoltaic experiments.     

Determination of trace inorganic anions in anionic surfactants by single-pump column-switching ion chromatography

An ion chromatography method has been proposed for the determination of three common inorganic anions(chloride,nitrate and sulfate) in anionic surfactants using a single pump system.The new system consists of an ion exclusion column,a concentrator column,and an anion exchange column connected in series via two 6-ports valves in a Dionex ICS-2000 ion chromatograph.The valves were switched several times for removing surfactants,concentrating and separating the three anions.The chromatographic conditions were optimized.Detection limits(S/N = 3) were in the range of 0.10-0.68μg/L.The relative standard deviations(RSDs) of peak area were less than 4.6%.The recoveries were in the range of 84.1-112.6%.     

微流动注射进样-加热雾室-等离子体质谱测定血清中的铂

开发了一种基于雾化室加热的微流动注射进样系统,并用于血清中Pt的测定。该进样系统由微量毛细管雾化器、加热微型雾化室、八通道十六孔多功能旋转阀、蠕动泵和注射泵组成。研究了雾化室尺寸、加热温度和采样环体积对信号强度的影响。当雾化室内径为9 mm、加热段长度为6 cm,雾化室温度90 ℃,采样环体积为5 μL时,195Pt的信号强度提高了2.31倍,同时信号精密度从5.1%降至2.2%,并得到峰形良好的信号峰。该进样系统的试样消耗小、灵敏度和检出限均优于常规进样系统。10次测定10 μg/L的Pt标准溶液和血清样品溶液,峰高的RSD分别为2.9%和3.3%。该进样系统测得10个血清中的Pt含量与常规进样系统的测试结果无显著差异,在样品量稀少的情况下具有良好的应用价值。     

在线样品前处理大体积进样离子色谱法直接测定海水中亚硝酸盐、硝酸盐和磷酸盐

采用戴安公司谱睿(Pre)在线样品除氯技术,结合OnGuard Ba柱去除硫酸盐,建立了离子色谱直接测定海水中亚硝酸盐、硝酸盐和磷酸盐的方法。该方法以IonPac AG23为富集柱,高容量IonPac AS23为分离柱,淋洗液自动发生装置在线产生KOH溶液进行梯度淋洗,抑制电导检测。实验结果表明: 样品稀释5～10倍时,直接进样不会干扰目标物测定。当流速为1 mL/min、进样量为500 μL时,海水中NO~2-N、NO~3-N、PO3~4-P的方法检出限分别为0.3、0.4、0.2 μg/L,线性范围分别为10～500 μg/L、14～680 μg/L、3.4～170 μg/L,线性相关系数r均大于0.9990。测得人工海水样品中目标物的加标回收率为92%～106%,相对标准偏差(RSD, n=6)为1.2%～7.7%。该方法一次进样可在13 min内完成分析,具有操作简单快捷、无污染等优点,能满足近海海水中NO~2、NO~3、PO3~4的定量分析要求。     

流动注射-电化学发光法测定煤灰中痕量钼(Ⅵ)

基于钼(Ⅵ)在-0.60V(vs.Ag/AgCl)电位下在线还原为钼(Ⅲ),且在碱性条件下钼(Ⅲ)与鲁米诺发生化学发光反应,据此提出了流动注射-电化学发光法测定煤灰中痕量钼(Ⅵ)的方法。钼(Ⅵ)的质量浓度与化学发光强度的增加值在5.0×10-7～5.0×10-4g.L-1范围内呈线性关系,检出限(3s/k)为5×10-8g.L-1。对1.0×10-6g.L-1钼(Ⅵ)标准溶液进行11次测定,测定值的相对标准偏差为2.6%。方法可用于煤灰中痕量钼(Ⅵ)的测定,测定值与国标方法测定值相符。     

Impact of impregnation pressure on desulfurization performance of Zn-based sorbents supported on semi-coke

High-pressure impregnation, a new preparation method for sorbents to remove H2S from hot coal gas, is introduced in this paper. Semi-coke (SC) and ZnO is selected as the support and active component of sorbent, respectively. The sorbent preparation process includes high-pressure impregnation, filtration, ovendry and calcination. The aim of this research is to primarily study the effects of the impregnation pressure on physical properties and desulfurization ability of the sorbent. The desulfurization experiment was carried out in a fixed-bed reactor at 500°C and a simulated coal gas used in this work was composed of CO (33 vol%), H2 (39 vol%), H2S (300 ppm in volume), and N2 (balance). Experimental results show that the pore structure of the SC support can be improved effectively and ZnO active component can be uniformly dispersed on the support, with the small particle size of 10-500 nm. Sorbents prepared using high-pressure impregnation have better desulfurization capacity and their active components have higher utilization rate. P20-ZnSC sorbent, obtained by high-pressure impregnation at 20 atm, has the best desulfurization ability with a sulfur capacity of 7.54 g S/100g sorbent and a breakthrough time of 44 h. Its desulfurization precision and efficiency of removing H2S from the middle temperature gases can reach <1 ppm and >99.7%, respectively, before sorbent breakthrough.     

流动注射-化学发光法测定富马酸依美斯汀

在酸性条件下,KMnO4与甲醛能够产生微弱的化学发光,而富马酸依美斯汀的存在能够大大增强该化学发光强度;结合流动注射技术,建立了测定富马酸依美斯汀的流动注射-化学发光新方法。该方法的线性范围分别为3.0×10-8～2.0×10-7g/mL,2.0×10-7～1.0×10-6g/mL和1.0×10-6～8.0×10-6g/mL。检出限为1.0×10-8g/mL,对2.0×10-6g/mL富马酸依美斯汀滴眼液平行测定11次,其相对标准偏差为1.3%。该方法已成功应用于滴眼液中富马酸依美斯汀的含量测定。     

水辅助注塑PP/SAN共混物制品中横晶形成机理的研究

采用水辅助注塑(WAIM)设备,在不同的注水压力和熔体温度下制备了4种质量比(98/2,96/4,94/6和92/8)的聚丙烯/丙烯腈-苯乙烯共聚物(PP/SAN)共混物制品.采用偏光显微镜(POM)和扫描电子显微镜(SEM),研究了WAIM PP/SAN共混物制品的结晶形态和相形态.研究发现,高压水的穿透作用所引起的强剪切和快速冷却可诱导SAN在PP基体中原位成纤,并诱导PP在SAN纤维表面形成大量的晶核而最终形成横晶.SAN含量为4 wt%时,所形成横晶的含量随水压的提高而增加,随温度的降低而大幅增加.当SAN含量较低(2 wt%)时,制品中没有横晶形成.     

在线中和富集及标准加入离子色谱法测定大气吸收液中的痕量阴离子

建立了大体积进样后的在线中和富集及在线标准加入离子色谱法,实现了对大气碱性吸收液中痕量氯离子、亚硝酸根、硝酸根、硫酸根的直接测定。比较了不同阀切换时间窗及在线中和柱的选择,确定了最佳的实验条件。利用戴安公司“谱睿”在线中和技术,通过Inguard H在线中和柱和CRD 200在线二氧化碳去除装置的共同作用,有效地去除了碱性吸收液中的OH~和CO2~3,使测定干扰降低到最小;通过大体积进样和在线富集,改进了样品的检出限,Cl~, NO~2, NO~3和SO2~4的检出限分别为17.5、171、34.7和42.4 ng/L;在线标准加入解决了痕量阴离子标准溶液的配制难题及NO~2低回收率对检测结果的影响。本方法实现了自动化分析,结果准确,重复性好,检测效率高,可用于常规离子色谱条件下无法测定的强碱性基体样品中痕量阴离子的准确测定。