Published: Jan 2008
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AS WE HAVE SEEN IN PREVIOUS CHAPTERS, THE measurement of distillation and vapor pressure characteristics are vital pieces of information for the classification and volatility property certification of petroleum products. While these measurements are typically conducted under standard laboratory conditions and practices, there also exists a need for measurement of these same parameters under the dynamic conditions encountered during the actual production process of these fuels and other products. This chapter provides a high level, non-technical overview to introduce readers to the subject matter. Measurements under these types of dynamic conditions are generally accomplished through the application of on-line analytical instrumentation systems. These systems are designed to tap, either directly or indirectly, into the process streams contained within a refineries production facility. These systems are generally capable of making continuous or periodic measurements of the distillation or vapor pressure characteristic during the actual dynamic production of the product. This provides for near continuous feedback of information about the volatility characteristics of a product directly to the process plant operators, such that the necessary adjustments to key process parameters can be made in order to have the final product meet the desired (or targeted) volatility properties. In modern day refineries, this process control function is typically carried out through automated control systems based on complex mathematical models of the manufacturing process, with the plant operators acting primarily in a supervisory role and to deal with unexpected disturbances. Last but not least, the on-line measurement system produced results can be used in providing continuous quality control and statistical analysis of the volatility properties of the monitored product stream. The design of these on-line measurement systems is non-trivial. For most applications, the design considerations begin with the process control requirement and objective. Since these systems are intended to operate continuously, unsupervised, and within the production facility, system hardware design must meet specific safety requirements and standards developed through ASTM, ISA, and other industry consortiums.
Lau, Alex T. C.
Imperial Oil-Eng Service, Toronto, Ontario
Collier, Michael A.
Petroleum Analyzer Company LP, Wilmington, IL