A Flow Stream Approach for Process Cell Modularization

Overview:

Many S88 implementation reports raise the issue of Process Cell breakdown into its lower level components (Units, Equipment Modules and Control modules). From the “Top-Down” to the “Bottom-Up” through the mixed approaches, each project involves user preferences through specific guidelines. The S88 standard does not provide much information for the specification of Control and Equipment modules boundaries. However, S88 provides more consistent guidelines to define the upper entities of process and procedural models. First issued in 1988, ASTRID complies surprisingly smoothly with S88. Its formalized bottom-up approach based on analytical check-up of material and energy flows, naturally leads to elementary equipment entities and process functionalities definition. Conversely, ASTRID leaves the field empty for higher-level considerations covered by S88. The respect of its pragmatic guidelines leads to straightforward, quite human independent, implementation. This results in highly structured functional specifications and robust implementations that are greatly appreciated for control systems design and Operational Qualification. This paper presents the main features of this methodology, a position statement regarding S88, the successes and issues after more than 10 years of development and implementation experience. This methodology is mainly supported by Rhone Poulenc and implemented in its French chemical and pharmaceutical plants. Its ambition is to be adopted by other companies and abroad as an S88 Guideline companion.