TABLE OF CONTENTS The first problem when designing processes involving hydrates is to predict the conditions of pressure and temperature at which hydrates will form. To begin the discussion of this topic, there are a series of methods that can be used without a computer. These are the so-called hand calculation methods because they can be performed with pencil and paper.
Hand calculation methods are useful for rapid estimation of hydrate formation conditions. Unfortunately, the drawback to these methods is that they are not highly accurate. In general, the less information required as input, the less accurate the results of the calculation; however, these methods remain quite popular.
Two methods are commonly employed for rapidly estimating the conditions at which hydrates will form. Both are attributed to Katz and co-workers. This leads to some confusion because both methods are often referred to as "the Katz method" or "Katz charts," although both methods actually involve charts. Here the two methods are distinguished by the names "gas gravity" and "K-factor." Both of these methods are presented here in some detail. A third chart method proposed by Baillie and Wichert (1987) is also discussed in this chapter.
The gas gravity method was developed by Professor Katz and co-workers in the 1940s. The beauty of this method is its simplicity, involving only a single chart. The chart is simply a plot of pressure and temperature, with the specific gravity of the gas as a third parameter. Two such charts, one in SI Units...
