(80c) Systematic Design and Intensification of Shale Gas Utilization Processes

Authors: 
Monjur, M. S., Artie McFerrin Department of Chemical Engineering, Texas A&M University
Demirel, S. E., Artie McFerrin Department of Chemical Engineering, Texas A&M University
Hasan, M. M. F., Artie McFerrin Department of Chemical Engineering, Texas A&M University
Li, J., Artie McFerrin Department of Chemical Engineering, Texas A&M University
Recent advancements in hydraulic fracturing and horizontal drilling have led to a boom in shale gas production [1]. The availability of cheap natural gas resources presented many opportunities to the petrochemicals, chemicals, and fuel industries [2]. Because of its wide variety of composition, numerous products can be made from shale gas. Several reforming alternatives of methane are available for producing synthesis gas (syngas) which is a building block for many value-added chemicals [3]. One such chemical compound is methanol, which has varied potential uses. It can be used as a clean-burning liquid fuel; energy carrier; and an intermediate for the production of several vital chemical products like olefins, formaldehyde, methyl tertbutyl ether, dimethyl ether and acetic acid [4-5]. Reforming reactions require high temperatures to operate, which makes these technologies cost intensive [3]. Additionally, as the quality of syngas can dictate the type of end-product and reaction products are needed with high purity, several energy-intensive separation methods are utilized. Systematic design methods can be highly useful, here, to screen, generate and yield novel intensified processing routes. However, traditional conceptual design methods rely on unit operation-based representations which may prohibit identification of such innovative solutions. To this end, recently introduced building block-based representation [6] provides several unique advantages for identification and automatic generation of intensified flowsheet variants.

In this work, building block-based design and intensification approach is used for the synthesis and intensification of shale gas utilization systems. Building block-based superstructure provides an optimization-based methodology toward incorporating process intensification in the conceptual design stage [7]. It is formed by collecting building blocks in a two-dimensional grid and can be used to automatically generate many different flowsheet variants [8]. In this representation, several physical and chemical phenomena, e.g. reaction, vapor-liquid equilibrium, gas-liquid equilibrium, etc., can be represented either as a ‘single block’ or via multiple neighboring blocks. For example, membrane modules are represented as a collection of two blocks separated by a membrane boundary. Similarly, vapor-liquid contact is represented as two neighboring blocks sharing a common boundary for phase contact. We formulate this block superstructure as a mixed integer nonlinear programming optimization (MINLP) problem. This MINLP model is then solved with cost and sustainability objectives to obtain several intensified flowsheet variants. We will present several intensified flowsheet alternatives that yield less total annual cost compared to the base-case design reported in the literature [9].

References:

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[6] Demirel, S. E., Li, J., and Hasan, M. M. F., Systematic Process Intensification using Building Blocks, Computers and Chemical Engineering 2017, 105, 2-38.

[7] Li, J.; Demirel, S.E.; Hasan, M.M.F., Process Synthesis using Block Superstructure with Automated Flowsheet Generation and Optimization, AIChE Journal, 2018, Vol. 64, Issue. 8, 3082-3100.

[8] Demirel, S. E., Li, J., and Hasan, M. M. F., A General Framework for Process Synthesis, Integration, and Intensification, Industrial & Engineering Chemistry Research (2019), DOI: 10.1021/acs.iecr.8b05961.

[9] Ehlinger, V. M., Gabriel, K. J., Noureldin, M. M. B., El-Halwagi, M. M., Process Design and Integration of Shale Gas to Methanol, ACS Sustainable Chemistry & Engineering 2014 2 (1), 30-37