Phase Equilibria for Natural-Gas Production. Calculation of Multicomponent Thermodynamic Properties Near-to and Far-From Critical

摘要CTS-9911744 J。普劳斯尼茨大学美国的天然气工业是一个每年数十亿美元的产业。 天然气生产效率的小幅提高可以带来巨大的经济利益和对有限自然资源的可观保护。天然气威尔斯井的有效生产需要定量地了解在相当大的温度范围内以及包括临界区域在内的广泛的组成和压力范围内的混合烃气液平衡。 由于实验数据是有限的各种合成天然气混合物，有一个很好的相行为的现象学图片，但是，计算这些平衡，我们没有一个令人满意的分子热力学方法，是可靠的，在所有地区的实际利益，即，近和远（汽-液）临界区。 这项研究旨在使用应用统计力学的最新结果来产生这样一种方法：由Chapman、Radocz等人发展的Wertheim（短）链流体理论，结合Lue和Prausnitz最近发展和扩展的白色混合物的重整化群（RG）理论，RG理论的实质是把一个“经典”的在远离临界点的条件下不重要但在临界点附近变得非常重要的密度波动的状态方程修正。 白色的方法（Lue和Prausnitz扩展），在一个相对简单的方式，从而大大提高了计算能力，相平衡附近和远离临界区域这项工作的最终目标是提出一个理论为基础的，面向工程的计算机程序设计工程师在化石燃料工业中直接使用。 这项研究将产生新的工程科学知识。 它将扩展，修改和综合统计力学的最新进展，以实现重要的应用。

ABSTRACTCTS-9911744J. PrausnitzU. of California @ BerkeleyThe natural-gas industry in the US is a multibillion-dollar per year industry. Small increases in efficiency in natural-gas production can bring very large financial advantages and appreciable conservation of a finite natural resource.Efficient production from natural-gas wells requires a quantitative understanding of mixed-hydrocarbon vapor-liquid equilibria over a fair range of temperature and a wide range of composition and pressure, including the critical region. Because experimental data are available for limited variety of synthetic an natural gas mixtures, there is a good phenomenological picture of phase behavior; but, for calculating these equilibria, we do not have a satisfactory molecular-thermodynamics method that is reliable in all regions of practical interest, that is, near-to and far-from the (vapor-liquid) critical region. This research is directed at producing such a method using recent results from applied statistical mechanics: Wertheim's theory for (short) chain fluids as developed by Chapman, Radocz and others, coupled with renormalized-group (RG) theory of White recently developed and extended top mixtures by Lue and Prausnitz.The essence of RG theory is to include in a "classical" equation of state corrections for density fluctuations that are not important at conditions remote from critical but become very important near the critical point. White's method (as extended by Lue and Prausnitz) does that in a relatively simple way, thereby much improving the ability to calculate phase equilibria near to and far from the critical region.The ultimate goal of this work is to present a theoretically based, engineering-oriented computerized procedure for direct use by design engineers in the fossil-fuel industries. This research will produce new engineering-science knowledge. It will extend, modify and synthesized recent advances in statistical mechanics toward significant application.