Process Modeling and Techno-Economic Analysis of Thermo-Catalytic Dimethyl Ether Synthesis and Microwave-Based Aromatics Production Technologies from Shale Gas

Abstract

Production of dimethyl ether (DME) and direct non-oxidative methane dehydroaromatization (DHA) to aromatics via conventional and microwave (MW)-assisted processes are investigated in this research. Plant-wide models of the shale gas to DME process with integrated CO2 capture via direct and indirect synthesis routes have been developed. Optimal parameter estimation, and model validation are undertaken for various sections of the process including the pre-reforming reactor, auto-thermal reforming reactor, DME synthesis reactors, CO2 capture units and separation sections. A novel DME separation process has been developed for efficient separation of DME, syngas, and CO2. Plant-wide techno-economic optimization is performed in an equation- oriented environment for maximizing the net present value (NPV). Effects of key design parameters and investment parameters on the process economics have been evaluated. For the conventional as well as MW-assisted direct non-oxidative methane dehydroaromatization (DHA) process, dynamic data reconciliation, parameter estimation, and multi-scale, multi-physics dynamic fixed-bed reactor model development are undertaken. Due to rapid coke formation, catalysts in the non-oxidative methane DHA reactors get deactivated. A model for the catalyst deactivation is proposed along with rate models for other DHA reactions. An algorithm is developed by coupling an iterative direct substitution approach with an optimization algorithm for optimal estimation of the initial state of the reactor and the kinetic parameters using the in-house experimental data. For the MW-assisted reactor, the amount of heat generated at specific catalyst sites has been modeled using Maxwell’s equation. For integrating the Maxwell’s equation within the process model, a reduced order model is developed. A 2-D multi-scale heterogeneous industrial scale MW rector model is developed by coupling the catalyst pellet level model with the reactor level model. In addition, plant wide models are developed, and techno-economic analysis of the conventional and MW-assisted processes are performed.