Quann R J
Mobil Technology Company, Paulsboro, New Jersey 08066, USA.
Environ Health Perspect. 1998 Dec;106 Suppl 6(Suppl 6):1441-8. doi: 10.1289/ehp.98106s61441.
Determining the complete molecular composition of petroleum and its refined products is not feasible with current analytical techniques because of the astronomical number of molecular components. Modeling the composition and behavior of such complex mixtures in refinery processes has accordingly evolved along a simplifying concept called lumping. Lumping reduces the complexity of the problem to a manageable form by grouping the entire set of molecular components into a handful of lumps. This traditional approach does not have a molecular basis and therefore excludes important aspects of process chemistry and molecular property fundamentals from the model's formulation. A new approach called structure-oriented lumping has been developed to model the composition and chemistry of complex mixtures at a molecular level. The central concept is to represent an individual molecular or a set of closely related isomers as a mathematical construct of certain specific and repeating structural groups. A complex mixture such as petroleum can then be represented as thousands of distinct molecular components, each having a mathematical identity. This enables the automated construction of large complex reaction networks with tens of thousands of specific reactions for simulating the chemistry of complex mixtures. Further, the method provides a convenient framework for incorporating molecular physical property correlations, existing group contribution methods, molecular thermodynamic properties, and the structure--activity relationships of chemical kinetics in the development of models.
由于分子成分数量庞大，利用当前的分析技术确定石油及其精炼产品的完整分子组成是不可行的。因此，在炼油过程中对这种复杂混合物的组成和行为进行建模是沿着一种称为集总的简化概念发展而来的。通过将整个分子成分集分组为少数几个集总，集总将问题的复杂性降低到可管理的形式。这种传统方法没有分子基础，因此在模型制定中排除了过程化学和分子性质基本原理的重要方面。一种称为面向结构集总的新方法已经被开发出来，用于在分子水平上对复杂混合物的组成和化学性质进行建模。核心概念是将单个分子或一组密切相关的异构体表示为某些特定且重复的结构基团的数学结构。然后，像石油这样的复杂混合物可以表示为数千个不同的分子成分，每个成分都有一个数学标识。这使得能够自动构建具有数万个特定反应的大型复杂反应网络，用于模拟复杂混合物的化学性质。此外，该方法为在模型开发中纳入分子物理性质相关性、现有的基团贡献方法、分子热力学性质以及化学动力学的结构 - 活性关系提供了一个方便的框架。
