Thermodynamic optimization of steady-flow industrial chemical processes

International Journal of Industrial Chemistry

دوره 9، شماره 4، اسفند 2018، صفحه 353-361

نوع مقاله: research article

شناسه دیجیتال (DOI): https://doi.org/10.1007/s40090-018-0164-1

نویسندگان

Leslie Glasser^{* 1}؛ James Alistair Fox²؛ Diane Hildebrandt²؛ D. Glasser³

¹Department of Chemistry, Curtin Computational Group, Curtin University, GPO Box U1987, Perth, WA, 6845, Australia

²Materials and Process Synthesis (MaPS), College of Civil and Chemical Engineering, University of South Africa, Florida Science Campus, Pretoria, South Africa

³University of South Africa, 5th Floor, Pha-Pha Building, Cnr. Pioneer and Christian De Wet Road, Private Bag X6, Florida, Johannesburg, 1710, South Africa

چکیده

Industrial steady-flow chemical processes are generally organised as a sequence of individually optimised operations. However, this may not achieve overall optimization since material (as recycle), heat and work transfers overall may not be well balanced. We introduce the idea of a preliminary overall thermodynamic balance to produce a reversible process, with the objective of minimising, for both economic and environmental reasons, the quality and quantity of energy used. This balance may later require adjustment to account for the realities of available materials and equipment. For this purpose, we introduce (i) a Carnot temperature, T_Carnot, by which a Carnot machine (an engine which can operate as either a heat pump or a turbine) can supply the required heat at the correct temperature for a process to operate reversibly, that is with least energy, and (ii) the GH Diagram on which Carnot temperature-based processes are plotted in ∆G–∆H space. We demonstrate the utility of this analysis by simple application to the Haber–Bosch process for ammonia synthesis and by a sequence of operations for the synthesis of methanol. We also briefly introduce the state function exergy, which uses the natural environment as the reference base for energy in place of pure elements under standard conditions.

کلیدواژه‌ها

Reversible · Carnot temperature · Energy · Exergy