This semester I took Capstone 1: Process Design, which is a weird amalgamation of separations, Aspen modeling, and economics in chemical engineering.

Northeastern believes rather than have a dedicated course for separations, you’re supposed to learn it throughout all of your coursework. We do learn some, primarily as tangents, but it is in this course we learn the theory for distillation columns, flash drums, adsorber columns, and some related operating equations. Additionally, we learn how to model these operations and more through ASPEN Plus, which is an amazingly powerful program once you can get it working. Finally, the course focused on economics of chemical plants. Creating Class V/IV estimates, comparing pieces of equipment, accounting for inflation, calculating internal rate of return, and so on.

The course completed with a project that was worked on throughout the semester. In my groups case, it was to create and model a chlorobenzene plant. The full project description can be found here on page F-5. The goal is to manufacture 20,000 metric tons per year of 99.7% pure monochlorobenzene and at least 2,000 metric tons of 99.6% p-dichlorobenzene a year. Being over-achievers, we decided to up the requirement to 100,000 metric tons per year of monochlorobenzene and 10,000 of p-dichlorobenzene. Our project shows a PID of the system, explaining the technological choices, and the economic potential of such a plant. Requirements 2 and 3 in the project description, full mechanical details and sketches for distillation column design, were not required for this project. The course did not go into the finer details of distillation column design, just McCabe-Thiel theory.

Below is the final report we handed in. Most of the pages at the end are MSDS’s for the chemicals that would be used in our processes.

Aspen is a really neat program but I would be lying if I didn’t want to start banging things against the wall. There were a few times where four hours of effort would be lost thanks to Aspen crashing and corrupting the saved file with it. The fact you can model distillation columns so accurately or multiple phases in a reactor is awesome, and something I would like to learn one day. But for this project, I think it was enough Aspen for now. Economic analysis was interesting to learn how quickly money went into the millions of dollars. Or that the primary cost of business is the raw material cost.