This introductory chapter follows the contours, and in some cases even the exact wording, of Chapter 1 in Spouted Beds, the only book prior to the present publication that deals exclusively with this subject. Indeed, the current venture was originally to be a revised version of that 1974 book by the present editors. However, after writing the first draft of this chapter for the revision, we realized that the breadth and variety of work on spouted and spout-fluid beds since 1974 required input from a wide range of authors for coverage to be completed in a finite time. Changes in the subsequent draft were mainly with respect to layout of chapter topics (Section 1.6). Despite advances since 1974, the earlier book of that year remains a repository of useful information not available in this volume or elsewhere.

The spouted bed

Consider a vessel open at the top and filled with relatively coarse particulate solids. Suppose fluid is injected vertically through a centrally located small opening at the base of the vessel. If the fluid injection rate is high enough, the resulting high-velocity jet causes a stream of particles to rise rapidly in a hollowed central core within the bed of solids. These particles, after being carried somewhat beyond the peripheral bed level, rain back onto the annular region between the hollowed core and the column wall, where they slowly travel downward and, to some extent, inward as a loosely packed bed.

Spouted beds have now been studied and applied for more than 50 years; during this period there has been a continual output of research papers in the engineering literature, considerable efforts to apply spouted beds in agriculture-related and industrial operations, and five international symposia dedicated solely to spouted beds. The book Spouted Beds by Kishan Mathur and the first-named editor of this volume summarized the field up to 1974. Since then there have been several reviews, but none that have surveyed the entire field comprehensively, including aspects that were barely touched in the earlier book or that were entirely absent. Examples of new areas include mechanically assisted spouting, slot-rectangular spouted beds, spouted and spout-fluid bed gasifiers, spouted bed electrolysis, and application of computational fluid dynamics (CFD) to spouted beds.

Our original intention was to prepare a sequel to the Mathur and Epstein book, but we soon realized that this chore would be too daunting, especially in view of competing time commitments. We therefore adopted the idea of a multiauthored book for which we would provide editing and prepare a subset of the chapters ourselves. Our intent was to choose an international array of authors able to provide a truly comprehensive view of the field, fundamentals as well as applications. Almost all those whom we asked to participate agreed to do so, and they have been remarkably cooperative in submitting material, following instructions, and responding to requests for changes, many of these being editorial in nature.