The optimal design of pressure swing adsorption systems

Separation systems account for a major portion of the capital and operating expenses for many chemical and petrochemical processes. The correct choice and design of the separation system can have a large impact on the overall process profitability. It is thus important during the overall process design stage for the possible choices of the separation system to be designed with some degree of optimality.;The proposed design scenario uses problem decomposition and model simplifications to obtain a tractable problem size. Three aspects of the problem are studied in detail separately: cyclic scheduling, dynamic bed modeling, and design optimization. The insight gained from these studies is used to decrease the complexity of the design of the overall system.;The structure of the design optimization model is a mixed-integer nonlinear program (MINLP); the solution of which determines the optimal operating configuration, size, and operating conditions. The resulting structure is then verified by a detailed dynamic simulation of the system. Designing an "optimal" PSA system to remove methane from a hydrogen stream illustrates the approach.;This work presents a methodology to determine the annualized cost optimal design of a pressure swing adsorption (PSA) separation system. Design decisions include the number of beds, the operations to use, the scheduling of those operations, and the operating conditions. Operations include adsorption, pressure equalization, blowdown, desorption, and feed repressurization. Interconnected operations, such as pressurizing one bed by connecting it to another which is to be depressurized, can be modeled.