Simon T. Holland

Novel separation system design using “moving triangles”

Abstract Shortcut design techniques have been employed in the initial design of traditional distillation systems. Current techniques are not useful in the design of novel or complex configurations however. We will show that by using column profile mapping “moving triangles” to model the behaviour of column sections (CS), any distillation configuration, no matter how complex, can be modelled and its behaviour more thoroughly understood. As an example, a thermally coupled column will be modelled using column profile maps. It is suggested that by gaining an understanding of the behaviour of the configuration quickly and easily, using column profile maps, time and money can be saved by avoiding poor initial decisions and designs.

Column profile maps as a tool for synthesizing complex column configurations

Abstract There has recently been a renewed interest in the design of distillation processes due to rising energy cost and growing environmental concerns. Column profile maps (CPMs) have been developed as a graphical tool to simplify the design procedure of distillation schemes as well as a method for analyzing existing processes. Using CPMs one is able to change topology within the composition space to suit the requirements of the separation and hence many separations that have been thought of as difficult or unviable can now be better understood and consequently new designs may be devised. The CPM technique has also been proven to be extremely useful as a design tool for complex columns, as configurations irrespective of complexity can be modeled and graphically understood. This paper aims to summarize the most important and interesting results and applications obtained using the CPM technique. It shows how CPMs may be used to synthesize complex columns like a Petlyuk or Kaibel column, as well as showing how new sharp split separations can be devised.

Expanding the operating leaves in distillation column sections by distributed feed addition and sidestream withdrawal

Publisher Summary This chapter describes the process of the expansion of operating leaves in distillation column sections by distributed feed addition and sidestream withdrawal. The synthesis of feasible distillation columns for multi-component mixtures is a major objective in the field of distillation. Traditionally, distillation columns are divided into rectifying (above the feed point) and stripping sections (below the feed point). Recently, a methodology to model feed addition, by using the difference point equation, has been introduced. This chapter shows the way to apply this approach to distributed feed addition over several trays. It makes use of column profile maps to show that the operating leaf can be expanded passed the residue curve. The chapter also incorporates the work of Glasser by considering sidestream withdrawal, to get the fully extended region of the operating leaves. In this connection, the chapter analyzes the difference point equation for feed addition and sidestream removal.

Make distillation boundaries work for you

Abstract There has been much discussion in the literature regarding whether column profiles can cross distillation boundaries and by how much. The traditional crossing of boundaries demonstrated by Wahnschafft et al. (1993) represents a very constraint case and was of academic interest only as the operating region for columns was small. The goal of this paper is to show how the design by using column sections and the difference point equation can extend the operating region for columns crossing distillation boundaries and therefore allow for more feasible separations.

Modeling Coupled Distillation Column Sections Using Profile Maps

Publisher Summary Differential equations (DEs) have been employed in the preliminary design of distillation columns. The properties of DEs have also been used to gain an understanding of the general behaviour of distillation systems. These approaches have, until now, only been applied to traditional distillation column configurations. There are however, potentially very exciting gains to be made in separation, by exploring alternative distillation configurations. This chapter discusses one of such configurations—a coupled column system. The behavior of distillation column sections can be approximated using differential equations. As a result of the equal liquid and vapor flows on either side of a coupled system, simple mass balance dictates that the difference vector remain constant throughout each column. The difference vectors of the columns have equal magnitude but opposite direction. Coupled column section profiles are described in the chapter with illustrations and figures.