The smooth fractionator

A modification of the general fractionator sampling technique called the smooth fractionator is presented. It may be used in almost every situation in which sampling is performed from distinct items that are uniquely defined, often they are physically separated items or clusters like pieces, blocks, slabs, sections, etc. To each item is associated a ‘guesstimate’ or an associated variable with a more‐or‐less close – and possibly biased ? relationship to the content of the item. The smooth fractionator is systematic sampling among the items arranged according to the guesstimates in a unique, symmetric sequence with one peak and minimal jumps. The smooth fractionator is both very simple to implement and so efficient that it should probably always be used unless the natural sequence of the sampling items is equally smooth. So far, there is no theory for the prediction of the efficiency of smooth fractionator designs in general, and their properties are therefore illustrated with a range of real and simulated examples. At the cost of a slightly more elaborate sampling scheme, it is, however, always possible to obtain an unbiased estimate of the real precision and of some of the variance components. The only real practical problem for always obtaining a high precision with the smooth fractionator is specimen inhomogeneity, but that is detectable at almost no extra cost. With careful designs and for sample sizes of about 10, the sampling variation for the primary, smooth fractionator sampling step may in practice often be small enough to be ignored.     

催化分馏塔塔顶冷凝系统改造

对催化分馏塔顶冷凝系统存在的问题进行了分析，提出优化流程，应用表面蒸发式空冷器替代干湿联合式空冷器的改造方案，并设计实施，取得满意效果。     

INTEGRATING ALBEMARLE RESOLVE DESULFURIZATION TECHNOLOGY WITH NOVEL PETRO-CANADA PROCESS CONCEPTS IN COMMERCIAL FCCU OPERATIONS

The gasoline and distillate sulfur regulations promulgated throughout the world to reduce tail-pipe emissions are now strongly impacting refinery operations and investments. FCC gasoline is recognized as the principal contributor of sulfur to the gasoline pool and has become the focus for meeting the new specifications. The difficulty in removing sterically hindered sulfur species in the fluid catalytic cracking unit (FCCU) cycle oil drives up the hydrogen and investment costs for treating the distillates. Although installation of pre- and post-treatment facilities is planned by many refiners, other non-capital approaches such as undercutting are being evaluated to meet interim and future sulfur levels. Even when expensive treatment facilities are installed, operating costs can be lowered and the flexibility of the facility increased with improvements in the ability to remove sulfur in the FCCU. In this article, we detail Petro-Canada's experience in integrating Albemarle's RESOLVE sulfur reduction technology with a combination of innovative process ideas. These concepts include heavy naphtha recycle, coprocessing of hydrogen donor feeds, and recycle of light cycle oil (LCO) to a specially designed stripper reactor. Special attention is paid to the interaction of deep FCC feed hydrodesulfurization with the FCC performance. The results demonstrate that very low FCC gasoline sulfur levels can be achieved without significant capital investment through novel approaches to recycle, creative integration of cat feed hydrotreating unit (CFHTU)-FCCU designs and operations, and application of state-of-the-art sulfur reduction additive technology. An added benefit of the RESOLVE 950 sulfur reduction technology is the substantial elimination of sulfur oxides in the FCC flue gas. This has been observed in Petro-Canada operations and numerous other RESOLVE 950 applications around the world.     

分布式预测控制在空气分馏塔中的应用

在大型空分控制系统中,集中式控制由于在线计算量大,对计算机的要求较高。采用分布式预测控制,把复杂系统的控制过程分散到各个子系统中去,降低了计算的复杂度,同时提高了系统的可靠性。建立了分馏塔的数学模型,并拆分成若干个子系统,利用纳什优化原理,获得了全局最优解。仿真结果表明,该算法取得了较好的控制效果。     

Gasoline composition determined by H NMR spectroscopy

A fast and simple ¹H NMR spectroscopic method was developed for the concentration measurement of aromatic, olefinic and aliphatic fractions in gasoline samples. Simultaneously, individual components such as benzene, methyl tert-butyl ether and several dienes could be determined. The method relies on only a few, well-established assumptions about the molecular compositions and is therefore applicable to a broad range of gasolines. It is well suited for laboratories with high sample throughput since measurement time is short and all concentrations are determined within one NMR experiment. The method was applied to commercial gasolines and samples used in European round robin tests. Comparisons of NMR and round robin test results showed excellent agreement.     

Gasoline quality prediction using gas chromatography and FTIR spectroscopy: An artificial intelligence approach

This paper reports on analysis of 45 gasoline samples with different qualities, namely, octane number and chemical composition. Measurements of data from gas chromatography and IR (FTIR) spectroscopy are used to gasoline quality prediction and classification. The data were processed using principal component analysis (PCA) and fuzzy C means (FCM) algorithm. The data were then analyzed following the neural network paradigms, hybrid neural network and support vector machines (SVM) classifier. The IR spectra were compressed and de-noised by the discrete wavelet analysis. Using the hybrid neural network and multi linear regression method (MLRM), excellent correlation between chemical composition of the gasoline samples and predicted value of the octane number was obtained. About 100% correct classification for six different categories of the gasoline was achieved, each of which has different qualities.     

乙烯装置裂解气分馏及冷却的模拟计算

对于含有众多复什碳氢化合物的裂解汽油、裂解柴油和裂解燃料油等宽馏分以及氢、轻烃、大量水分的裂解气，采用虚拟组分以减少组分总数、用惰性气体描述水在烃类中的相行为，以物流混合和闪蒸过程组成一个闪蒸平衡级，并以逐级闪蒸计算来描述乙烯装置的裂解气分馏塔。     

The taxation effect on gasoline price asymmetry nexus: Evidence from both sides of the Atlantic

This paper explores the degree of competition in various gasoline markets and infers possible causes of price asymmetry across the globe. For this purpose we use the Dynamic Ordinary Least Square method in order to estimate price asymmetry in twelve European countries and the United States for a sample of weekly observations which spans the period from June 1996 to August 2011. The results indicate the common perception that less competitive gasoline markets exhibit price asymmetry, while highly competitive gasoline markets follow a symmetric price adjustment path. Finally, the inclusion of taxes (VAT and excise tax) into retail gasoline prices, supports the existence of price asymmetry in many European countries.     

汽油加氢装置分馏部分模拟优化

随着国家新一轮汽油质量升级的实施,国内研发了多种催化汽油加氢技术。应用PROII软件,利用Distillation、Flash及Simple HX模块,模拟了120万t/a汽油选择性加氢装置的轻、重馏分分馏,并对分馏塔的控制因素、操作因素进行研究,最终确定了装置的设计操作条件,实现了生产合格低硫汽油产品以及减少设备投资及操作费用的目的。     

浅谈大型分馏塔内件安装的常见问题及整改措施

分馏塔是蜡油加氢裂化装置分馏系统最重要的设备,其运行好坏直接影响产品质量。而分馏塔塔径大,塔内件安装难度突出,故其施工和验收要格外仔细。本文主要介绍在安装大型分馏塔内件过程中出现的一些常见问题,并根据其原因提出了相应的整改措施。