A nonlinear approach to design of process systems is presented and applied to glycerol etherification plant. Depending on the operational parameters, the system shows either two or no steady states. Moreover, the flow rates are constrained by the available equipment. The critical manifolds separating the stability/instability and feasibility/unfeasibility domains should not be crossed when the system is disturbed or the design parameters are uncertain. Nonlinear analysis and constructive (synthesis- oriented) methods, ensuring the robustness of the design, are presented. The dynamic performance is assessed using rigorous process simulation in Aspen Dynamics.