New approach to dynamic distillation simulation: Accurate dynamic and steady state predictions in real-time

Scope of study. The goal of this study was to create a set of algorithms that would allow the simulation of the dynamic (transient) responses of distillation columns. This was to be accomplished without the need for prohibitive amounts of computing power (i.e. no more than a minicomputer). The simulation system was to have a modular structure such that blocks would be linked together via stream vectors to create any flow sheet desired. A database of pure component properties was to be available within the simulation system. The intended applications to be studied with this proposed simulation system were hydrocarbon systems.; Findings and conclusions. The results of this work are a set of algorithms, both steady and unsteady state, which can be used as building blocks to create a dynamic simulation of practically any distillation tower. A new overall technique for performing a dynamic distillation simulation was developed which uses these blocks. This simulation system will run in real-time, depending on both the size of the flowsheet and the computer hardware. An example of a crude tower was implemented on a DEC MicroVAX. This crude tower simulation reached the capacity of the MicroVAX for executing in real-time. Any addition to this flow sheet would have resulted in compute times that would have been excessive. However, this crude tower simulation is equivalent to 13 simple two product towers. The results presented in this work verify the steady state accuracy of this simulation system. The results presented regarding the transient response predictions are less concrete due to the source of data for comparison. However, these results at least verify the directions of responses are reasonable. A new technique for rating heat exchangers where the fluid is undergoing a phase change on one or both sides of the exchanger was presented. A new method for determining the individual tray temperatures in a trayed section was presented.