It's a good question, given the variety of jobs in the field. At the grad and post-grad level, chemical engineers overlap heavily with chemists and material scientists, a little less with mechanical and industrial engineers, biologists, and a dozen other fields.
At the undergrad/entry level, many chemical engineers end up becoming process or project engineers. Process engineers are hired to manage and optimize a handful of related industrial processes, whether it's brewing beer, baking snack food, refining oil, making pharmaceuticals, processing cleaning solvents, operating steam turbines for electricity, etc. They figure out how to optimize the reaction conditions, heat flow, product purification, etc., figure out what sensors are appropriate, and oversee equipment upgrades to be in compliance with federal regulation.