Supercritical water oxidation improvements through chemical reactors energy integration

Supercritical Water Oxidation (SCWO) is the process of complete destruction of toxic and hazardous organic wastes in a compact, totally enclosed system through oxidation in water brought to temperatures and pressures above its critical point: 374 °C and 218 atm. At these conditions, organic materials, gases and water form a new phase, completely mixed, that provides the environment for a rapid and complete oxidation. Typical products from a SCWO process include carbon dioxide, water, and inorganic salts or acids. SCWO advantages include very high destruction efficiencies, low NOx and SOx occurrence, no dioxins or furans, totally contained process, no smokestack, relatively low temperature operation, and compact size. The chemical reactors energy integration (CREI) concept focuses on, simultaneously, the entropy generation reduction of both chemical reactor network (CRN) and heat exchanger networks (HEN) and the search for possibly new operating conditions for some of the reactors (if not all) to accomplish this goal. The basic idea of CREI is to replace each of the reactors of the CRN with a corresponding virtual heat exchanger, having the chemical reaction enthalpy as thermal load, thus creating a virtual HEN. Then, combine this VHEN and the existing HEN into an extended system, which will be the object of the pinch analysis. Care should be taken that the virtual heat exchanger system produces the same amount of entropy as the replaced chemical reactor. Pinch and CREI analysis were applied to SCWO process and the suitable network configuration and operating conditions were found to achieve the minimum entropy generation.