几种微量氧分析仪在空分设备中的应用

介绍原电池型和氧化锆型微量氧分析仪的工作原理及日常维护经验,结合微量氧分析仪的选型和使用实践,介绍大型空分设备微量氧分析仪的选型经验。     

微量水分析仪在空分设备中的应用与维护

介绍微量水分析仪的工作原理及日常维护经验,结合青岛钢铁气体有限公司空分设备配套微量水分析仪的选用和实际使用情况,阐述空分设备微量水分析仪的选型经验。     

Minimization of air pollutants emissions by process improvement of catalytic reforming unit in an Iranian old refinery

The old oil refineries are largest chemical industries that are responsible for emission of several pollutants and GHGs. It is possible to minimize energy usage as well as air pollution by some process modification. The main objectives of this investigation were the minimization of air pollution and CO₂ emissions in catalytic reforming unit in an oldest and largest refinery in Iran. To assess the air quality, ten sampling stations were selected for measurement of CO, H₂S, SO₂, and PM₁₀ in ambient air. Also concentrations of C₁–C₅, H₂S, and CO₂ were measured in selected unit. In final, structural and process flaws were identified by analyzing real functional circumstances and they were modified. Results show that SO₂, H₂S, and PM₁₀ concentrations are higher than ambient air standard levels in all seasons. Also, according to achieved results, the cold separator gas flow rate is reduced from 38,936 kg/day (once-through gas process) to 9,649 kg/day (recycle gas process). Beside CO₂ and SO₂ emission rates will be reduced 1803 and 136.5 kg/day in this unit, respectively. Furthermore, the modification of this process causes prevention of 1654 kg CO₂ emission into the atmosphere, during each coke burning and catalytic regeneration.     

Multivariate calibration of on-line enrichment near-infrared (NIR) spectra and determination of trace lead in water

An on-line enrichment near-infrared spectroscopy (NIRS) technique was developed in order to improve the sensitivity for the determination of trace heavy metal lead. Trace Pb²⁺ was enriched by chelating resin with on-line enrichment equipment and then the enriched lead on the resin was directly determined by near-infrared diffuse reflectance spectroscopy without elution procedure for simplicity of measurements. Partial least squares (PLS) regression was used to build models between the corrected spectra and concentrations of Pb²⁺, and segmental cross-validation was used to search for a reasonable number of PLS factors. The results showed that NIR spectra and concentrations of Pb²⁺ had a good linear relationship with the maximum of correlation coefficient of 0.9228 in the 1006–1383 nm region. The minimum RMSEP was 0.4777 mg L^− 1 when the latent variable number was 5 by using the region of 1006–1383 nm. The limit of detection (LOD) of lead was 0.2384 mg L^− 1 in this case. This study demonstrates that the prediction of trace heavy metal lead concentrations by NIRS is feasible with enrichment technique.     

Flow-through dispersed carbon nanofiber-based microsolid-phase extraction coupled to liquid chromatography for automatic determination of trace levels of priority environmental pollutants

Handling of carbon nanoparticles as sorptive materials in a flow-through packed-bed mode has been to date hampered by undue pressure drop and deteriorated retention efficiency because of nanoparticle bundling and entanglement. To surmount this limitation, a dedicated stirred-flow sorptive microchamber integrated in a fully automated sequential injection (SI) assembly is herein proposed for expedient handling and reuse of carbon nanoparticles in microsolid-phase extraction (μSPE) procedures. The assembled setup features automatic uptake, preconcentration, and retrieval of target organic species using dispersed nanoparticles as a front-end to liquid chromatographic (LC) assays. Chlorotriazine residues (atrazine, simazine, and propazine) and dealkylated metabolites thereof (deisopropyltriazine (DIA) and deethylatrazine (DEA)) were selected as model compounds because of their electron-poor aromatic structure and potentially strong π-π interactions with electron-rich sorptive materials. The effect of several parameters on the analytical performance including the type and amount of nanoparticles (carbon nanofibers (CNFs), multiwalled carbon nanotubes (MWCNTs) and oxidized carbon nanotubes (MWCNT-COOH), the sample volume (breakthrough volume), the nature and volume of eluent, and the interface between the sample processing module and LC was explored in detail. Using dispersed CNFs at-line coupled to LC, absolute recovery percentages for 10 mL sample percolation were >94% for the overall herbicides with enrichment factors of ca. 20, limits of detection (S/N = 3) of 0.004-0.03 ng mL(-1), limits of quantification (S/N = 10) of 0.01-0.09 ng mL(-1) and repeatability within the range 0.5-1.8%. The SI-CNF-LC hyphenated system was harnessed to the analysis of not merely untreated environmental waters at concentration levels below those endorsed by the current EU Water Framework Directives but to crude soil extracts for which CNF reuse with no loss of retention efficiency was proven feasible by resorting to appropriate automatic regeneration procedures and internal standardization.     

Continuous extraction of trapped air from bubble ice or water for on-line determination of isotope ratios

We describe a new continuous extraction system for trapped air from bubble ice or water for on-line determination of the isotopic composition of the main air components nitrogen and oxygen (delta15N, delta18O, and delta17O). Studies of the composition of air from bubbles trapped in polar ice are providing fundamental information about ancient atmospheric composition and, therefore, are an important tool to learn more about Earth's climate. The new system proved to work reliably for standard air admixed and subsequently removed from a water stream. The precision (1 SD) of standard measurements is approximately 0.04/1000 for delta15N, approximately 0.1/1000 for delta18O, and approximately 0.15/1000 for delta17O. Ice measurements with the new on-line system are promising. Continuous measurements of nitrogen as well as oxygen isotope ratios can be performed with a spatial resolution of approximately 3 cm and nearly the same precision as for the standards. However, the measured delta values of ice are generally lower, as compared to ice measured with conventional techniques, as a result of a time-dependent dissolution process of air in water associated with kinetic fractionation, which affects standard and sample differently. By modeling the dynamics of the this dissolution process, we found a reason for the lack of accuracy and propose an improvement of the system that will lead to a better accuracy of the ice measurements.     

Real-time optimal spatiotemporal sensor placement for monitoring air pollutants

Clean Technologies and Environmental Policy - Air pollution exposure assessment involves monitoring of pollutant species concentrations in the atmosphere along with their health impact assessment...     

钢铁企业空分设备配置探讨

对新建钢铁企业空分设备配置中氧气纯度的选择、空分设备规模的配置方式和内、外压缩工艺流程的选择等几个方面进行了探讨,推荐了适用于钢铁企业的空分设备流程及配置。     

空分设备空气预冷系统循环水改造

由于空分设备循环冷却水系统水质不好,造成冷水机组、冷却器等内部结垢严重,导致设备运行不稳定。根据实际情况,将空分设备空气预冷系统的水系统独立设置,并对水系统设备进行防腐、自动控制等改造,大大提高了空分设备运行的安全性和稳定性。     

空分设备空气预冷系统循环水改造

由于空分设备循环冷却水系统水质不好，造成冷水机组、冷却器等内部结垢严重，导致设备运行不稳定。根据实际情况，将空分设备空气预冷系统的水系统独立设置，并对水系统设备进行防腐、自动控制等改造，大大提高了空分设备运行的安全性和稳定性。     

空气处理机组风阀控制算法分析

针对空气处理机组风阀常规PID控制算法中出现的2个风阀调节量不均衡、开机稳定慢的现象,提出一种基于串级PID控制的改进算法。首先根据阿里巴巴张北云计算数据中心二期工程中空气处理机组的实际运行情况搭建数学模型,然后利用该模型分别对常规PID和改进后的串级PID算法进行模拟运行与对比分析。结果表明,改进的串级PID算法使得2个风阀调节量均衡,并有效缩短系统进入稳定运行阶段的时间。     

高大空间空气处理单元气流组织特性分析

高大空间空气处理单元是一种新型的分散式高大空间空调末端,可有效改善冬季室内温度分层现象。以武汉市某火车站候车厅为例,采用CFD模拟方法对高大空间空气处理单元的不同送风角度和送风口尺寸下的冬季候车厅温度分布进行模拟,并与采用分层空调系统时的温度分布进行对比分析,该末端系统可减小33.3%的垂直温度差,进而减小21.3%的热负荷。本研究结果将为高大空间空气处理单元的实际应用提供一定的指导与参考。     

Fluorous affinity chromatography for enrichment and determination of perfluoroalkyl substances

The adsorption behavior of four perfluoroalkyl acids, including the environmentally relevant perfluorooctanoic acid, has been investigated on a straight-chain perfluorohexyl adsorbent. The aim of this study was to probe the potential of perfluorinated materials for the analysis and enrichment of perfluoroalkyl analytes. Water/acetonitrile mixtures, to which formic acid had been added (generally, 0.1%), were employed as mobile phases. For all perfluorinated acids, a U-shaped retention profile was observed by changing the amount of acetonitrile in the mobile phase. This behavior has been correlated to the excess adsorption of the organic component on the adsorbent surface. The concept of perfluoromethylene selectivity has been defined as the ability of a chromatographic system to discriminate between molecules that differ by a single perfluoromethylene group. The contribution to the Gibbs free energy of phase transfer for the passage of a perfluoroalkyl carbon from the mobile to the stationary phase has been evaluated. This information, in addition to the traditional van't Hoff analysis, has also been used to estimate the analogous contribution for the transfer of a carboxylic unit. Finally, insights into the retention mechanisms of perfluoroalkyl acids on straight-chain perfluorohexyl sorbents are discussed.     

离心风机在空气处理机组中的性能分析研究

如何快速而准确地预测离心风机在所设计的空气处理机组内的性能,对于产品设计人员来说非常必要,但也比较困难。本文介绍一种实用而较为准确地预测离心风机在空气处理机组中性能的方法,从试验方案、依据标准、数据分析和建模方法等几方面进行介绍和讨论。     

Adaptive K-NN for the detection of air pollutants with a sensor array

The field of air-quality monitoring is gaining increasing interest, with regard to both indoor environment and air-pollution control in open space. This work introduces a pattern recognition technique based on adaptive K-nn applied to a multisensor system, optimized for the recognition of some relevant tracers for air pollution in outdoor environment, namely benzene, toluene, and xylene (BTX), NO/sub 2/, and CO. The pattern-recognition technique employed aims at recognizing the target gases within an air sample of unknown composition and at estimating their concentrations. It is based on PCA and K-nn classification with an adaptive vote technique based on the gas concentrations of the training samples associated to the K-neighbors. The system is tested in a controlled environment composed of synthetic air with a fixed humidity rate (30%) at concentrations in the ppm range for BTX and NO/sub 2/, in the range of 10 ppm for CO. The pattern recognition technique is experimented on a knowledge base composed of a limited number of samples (130), with the adoption of a leave-one-out procedure in order to estimate the classification probability. In these conditions, the system demonstrates the capability to recognize the presence of the target gases in controlled conditions with a high hit-rate. Moreover, the concentrations of the individual components of the test samples are successfully estimated for BTX and NO/sub 2/ in more than 80% of the considered cases, while a lower hit-rate (69%) is reached for CO.